Guido Trentin (born 24 November 1975) is an Italian former professional road bicycle racer.

In 2000 Trentin, riding his first Tour de France, placed second in the young rider classification behind Francisco Mancebo.

Trentin moved onto the Cofidis team in 2001, and spent five years with the French squad.

Trentin recorded three wins beyond his stage victory in the 2002 Vuelta a España: overall victory in the 2003 Tour du Poitou Charentes et de la Vienne and stage wins in the 2005 Tour de Wallonie and 2005 Troféu Joaquim Agostinho.

This biographical article related to an Italian cycling person born in the 1970s is a stub.