Regina Carter, the young American jazz violinist, was not big enough to be considered a headline act at Ronnie Scott's a year ago. Now she is not only the main attraction, but she is eliciting a more vociferous response from the audience than has been heard there in a while.

Carter is a technically skilful violinist with a classical player's subtlety of nuance and dynamics. She is also a formidable improviser with an uninhibited relationship with her instrument. This leads her to swerve from fragile sounds to raucous hoe-down dissonances and back. Her current sojourn in London finds her with a group of her own making - and it's fascinating how direct and funky it is. Hard-hitting Latin fusion and African music play as big a part as the effervescent, Stephane Grappelli-like swing that is the orthodoxy for most violinists in jazz.

Compared with her wonderful duet performance with the pianist Kenny Barron in London earlier this year, this gig did not present the ideal opportunity to savour Carter's thoughtfulness and melodic imagination. But if this week's performance was more inclined towards big effects, there was still a lot of cliff-edge improvising in it, and the quartet is tight, well-matched and full of ideas. Milt Jackson's Motor City Moments (the title track of Carter's current CD) plays a prominent part, and a heated Latin-jazz feature, For Someone I Love, makes the quintet sound a lot bigger than it is - not least for Carter's singing and playing operating in engaging call-and-response mode, and Cuban percussionist Mayra Casales's furious drumming.

For Someone I Love tapped Regina Carter's openness to vocalised effects on the violin - laconic slurs, descending phrases like laughter - but Lady Be Good explored the grace of her playing, with vibrato-packed sounds turning into glittering swing. Drummer Alvester Garnett confirmed that he is a true expert in the demanding art of sounding expressive and supportive with brushes rather than sticks.

• Ends tomorrow. Box office: 020-7439 0747.