The move comes just three months after OutRage! activists disrupted a Romanian National Opera performance at the Royal Albert Hall in London by unravelling a huge banner with the slogan: "Romania - stop jailing queers".
Peter Tatchell, OutRage!'s most famous campaigner, said: "We are hoping that it won't just be gay people supporting this boycott but everybody who is concerned about human rights.
"Romania is now the only country in Europe that still outlaws male and female homosexuality."
Under a newly modified law, homosexual relations between consenting adults in Romania are punishable with up to five years' jail if they are conducted in public or if they are deemed to have caused a "public scandal".
The law represents a relaxation of the harsher legislation in force under the communist dictator Nicolae Ceausescu but when it was passed late last year it was immediately condemned by OutRage! and the human rights organisation Amnesty International as still being way out of line with West- and even East-European norms.
"The term 'public scandal' ...could still be used to imprison consenting adults," Ivan Fischer, an Amnesty spokesman, said. "Under this law anyone could go to the police and claim to be 'scandalised' by ... the effeminate behaviour of a neighbour."
The new law also makes it an offence for homosexuals to form their own associations or engage in acts of "propaganda" or "proselytising" - effectively banningtheir clubs, bars, newspapers or any other form of support.
According to Mr Tatchell, the law is in flagrant breach of Romania's promise to decriminalise homosexuality following its accession to the Council of Europe in 1993 and is a serious obstacle to its ambition to join the European Union.
Hopes for a genuine liberalisation of the law were raised in November when Emil Constantinescu was elected as president. He once promised to repeal the current legislation; in office, however, he has not chosen to push the issue.
Indeed, rather than liberalising the law, there are many in the country who would like to see a return to the Ceausescu-era legislation. Romania's powerful Orthodox church hasorganised mass petitions calling for the return of the blanket ban on homosexual practices, which it condemns as "the tyranny of selfish, barren passion".
Many of Mr Constantinescu's political allies in the governing Peasant Party also take a hard line. In last year's debates on the law, the Peasant Party MP Emil Popescu said that "incest is preferable to homosexuality," because it "gives breeding a chance". Horia Pascu, a party colleague, claimed that homosexuality was unknown in the animal world, except among ducks, "which are known to be the most stupid among birds".