Wales' Andrew Selby, Fred Evans and Zack Davies all claimed victories at the European Amateur Championships in Ankara, Turkey.
Selby defeated Hungary's Norbert Kalucza 28-11 to reach the last eight in the 52kg category.
Lightweight Davies beat Dmitry Galagot of Moldova 30-17 and welterweight Evans saw off German Araik Marutjan 13-8.
But there was disappointment for Khalid Yafai, who was superbly beaten 19-10 by Ireland's Michael Conlon.
England's Yafai, a silver medallist last year, was a pre-tournament favourite but could not get close to Conlon, who was competing in only his eighth senior fight.
Scotland's Josh Taylor progressed into the last 16 by defeating Koba Pkhakadze of Georgia on countback.
Ireland's Willie McLaughlin made it through in the welterweight division when he beat Croatian Borna Katalinic 20-14.
Michael McDonagh was unable to match his compatriots success, however, losing 16-6 to Valodymyr Matvichuk of Ukraine.