Newcastle regained the lead from Saracens on points difference and Rob Andrew's team also have a game in hand.
It took a while for the Falcons to get going but they were still able to build a 10-3 lead through a Jim Naylor try and a conversion and penalty from Andrew before their purple patch.
Tony Underwood raced over after linking with Stuart Legg and Pat Lam; Dean Ryan, the Newcastle captain, rounded off a drive by the pack and Alan Tait was on hand after Lam had carved open the Quins defence. That gave the home side an unassailable 31-3 half-time lead.
There was more of the same punishment for Harlequins in the second half as Underwood scored under the posts after a trio of Scottish internationals - Gary Armstrong, Doddie Weir and Tait - combined to create the opening.
After that Quins were spared as Newcastle took their foot off the accelerator and the visitors were able to salvage some pride with tries from Daren O'Leary and Dan Luger.
It was, however, Newcastle's day and they made sure that they had the final word when Martin Shaw, deep into injury time, forced his way over for a try.
With 11 home wins out of 11 in the league this season it is no wonder that Andrew, the director of rugby, is rapidly becoming a perfectionist.
"It took time for us to get out of our blocks, with many of the players minds on last week's internationals and those this weekend, but I wasn't totally concerned," he said. "Everybody wants to take our scalp, but, once we got going, we were okay."
Newcastle: Tries Underwood 2, Naylor, Ryan, Shaw, Tait; Conversions Andrew 5; Penalties Andrew. Harlequins: Tries Luger, O'Leary. Conversion Liley. Penalty Liley.
Newcastle: S Legg; J Naylor, A Tait, V Tuigamala, T Underwood; R Andrew, G Armstrong; N Popplewell, R Nesdale, P Van Zandvliet, G Archer, D Weir, P Lam, D Ryan (capt), R Arnold.
Harlequins: J Staples; D O'Leary, T Tollett, P Mensah, D Luger; J Liley, N Walshe; J Leonard, K Wood (capt), A Yates, L Gross, G Llewellyn, R Jenkins, B Davison, A Leach.
Referee: C White (Gloucester)
l Sale increased their chances of survival in the Allied Dunbar Premiership when beating Richmond 23-20 yesterday. Their New Zealand outside-half Simon Mannix contributed 10 of the points but was injured by Jim Fallon's tackle and, as he made his way off the field, fell over. The Sale medical team reported him as merely shaken-up.Reuse content