Theatre: Guys, guys, start arguing, please!

Hushabye Mountain English Touring Theatre Certain Young Men Almeida, N1 The Vagina Monologues King's Head, N1

There's a simple device in Jonathan Harvey's new play, Hushabye Mountain, that catches the evolving drama of Aids. The main character, Connor, used to go out with Danny; Danny died of Aids, and six months later Connor goes out with Ben. In scene after scene (bedroom, restaurant, brother's house) one boyfriend goes out of the room and the other one comes in. This way, we see the first relationship in tandem with the second.

The device also neatly captures the play's main theme: the continuing presence of the dead lover in the survivors' lives. In a hotel room Connor (Stuart Laing) tells new boyfriend Ben (Nick Bagnall) that the bed is Danny's. "This isn't Danny's bed," says Ben, unblinkingly, "This is Trusthouse Forte's bed."

The Danny story follows the familiar Aids landmarks: The Test, The Result, Telling People, Picking Music For Your Own Funeral. Ben's story starts with an anger which is, rather imaginatively, turned on the Queen. Ben works in Kensington Gardens and thinks, since so many homosexuals work at the Palace, the Queen should donate the odd Crown Jewel to medical research. Ben is HIV-positive too; but as the play progresses, so does Aids research, and he has a chance of survival. The story has moved on.

As you'd expect from the author of Beautiful Thing, Babies and the BBC2 sitcom Gimme Gimme Gimme, Harvey presents an amiably hedonistic world of doing coke, taking E, going clubbing, snogging on the beach and getting in the bath with another person and a couple of bottles of champagne.

His portrait of a bunch of pals is complex and affecting. Of the original four, two are gay, two are straight, two are brothers, two are best friends and two are married. The best scene in Paul Miller's production for English Touring Theatre, which opened last week in Crewe, comes when the four have a blazing row. I wished they'd had a few more.

Where Hushabye Mountain is hard to take is in the whimsical fantasy version of Heaven, to which Danny has been transported, with white robed figures and fluffy clouds, and Elizabeth Estensen rows around in a white boat doing the voice of Judy Garland. One of Harvey's characters points out that this is a stereotypical gay fantasy, based on musicals and movies. But Harvey still goes ahead and revels in it, giving us an abstract vision of a gay sensibility that's as fluffy as the clouds.

In the programme for Peter Gill's Certain Young Men, a colleague of Gill's describes his work as "one of the best-kept secrets in British theatre". Small Change, Kick For Touch, Mean Tears and Cardiff East have all been presented at the Royal National Theatre. Most playwrights in British theatre would give a lot to have a secret that is as well-kept as that.

Gill's reputation for severity takes another step forward in Certain Young Men. It's not just the props that are stripped back. Certain Young Men includes no women, no children, no babies, no old people, no middle- aged people and no black people. There are no neighbours, no meals, and no telephones. It's more of a retreat. Gill presents us with eight urban gay guys caught up in discussing what's the matter, why didn't you ring and where are you going now?

It's not much of a play. The series of duologues do develop, and there are a couple of overlaps as characters step from one to another. But you don't spend the interval wondering what's going to happen next. Certain Young Men is better seen as variations on a theme: a series of dramatic exercises about the nature of gay identity. It has the sealed-off intensity of a rehearsal.

Gill directs these duologues with a fastidious urgency. His first-rate cast, which includes Jeremy Northam as a cricket-playing doctor, give Gill the maximum of emotional commitment without tipping into indulgence. It's in the minute calibration of high-pitched feelings that Certain Young Men finds its energy. That comes more from the directing than the writing itself. Its narrow focus and slight plot, spread across two and a quarter hours, left me fatigued by the wrangling and introspection of the relationships.

The American playwright Eve Ensler interviewed more than 200 women in preparation for her one-woman show, The Vagina Monologues. The result is certainly an event. Ensler sits in front of a backdrop of Rothkoesque reds, with a microphone in front of her face and a stack of prompt cards on her knee. Her black hair curls round and frames her face like a helmet. She looks reluctant. The audience has the rapt enthusiasm of a revivalist meeting or group therapy. For Ensler has found a whole new taboo to break.

She introduces each monologue with throwaway remarks about how the monologue came to be written (sometimes a composite of a number of interviews, sometimes a fictionalised version of interviews) and how the monologue has been received in other cities. Then there's a shift in lighting, a pause, while she flicks her hair back and allows a little sincerity to fill up in the room (the Barbra Streisand moment), and then she's off.

I preferred the intros. The subject-matter is revelatory, but the presentation is slightly tense. Her monologues take us through reactions to the word itself, which Ensler says sounds like an illness, to a list of nicknames, to stories of sexual neglect, sexual fulfilment, rape and birth.

Ensler is a more daring interviewer than performer. The voices of the 200 women tend to flatten out when rewritten as monologues. Sometimes, as with Bosnian rapes, the material overwhelms her treatment of it. It's in the smaller anecdotal details that she makes the biggest impact. Here, there's a sense of embarrassment and loss from the women, and ignorance and misunderstanding from the men. At the King's Head, the audience was 90 per cent female. It would have been better news for women if the audience had been 90 per cent male.

`Hushabye Mountain': Liverpool Everyman (0151 709 4776), to Saturday and touring; `Certain Young Men': Almeida, N1 (0171 359 4404), to 20 February; `The Vagina Monologues': King's Head, N1 (0171 226 1916), to 8 March.