Gentile, a Caserta native, started his career at only 15, with local side Juvecaserta Basket, playing under head coach Bogdan Tanjević, in 1982.

[1][2] Gentile soon became a "big-time player" for Caserta, helping them qualify for the 1983–84 FIBA Korać Cup, which was their first participation in a European-wide competition.

[1] His defining feat during his Caserta career was his participation in the 1991 Italian League Serie A championship that was won by the Campanians.

[3] When owner Bepi Stefanel left Trieste, to go to Olimpia Milano in 1994, he also moved the whole squad to Milan, including Gentile and Tanjević.

In the next season, he reached the final of the SuproLeague (the renamed official successor to the FIBA EuroLeague), but this time Panathinaikos lost to Maccabi.

[3] Gentile returned to Italy in 2001, briefly playing with Snaidero Udine,[2] before finishing the season with the Italian second division side Pallacanestro Reggiana.

[5] Gentile next started a coaching career, with the Italian second division club, Andrea Costa Imola, for the 2006–07 season.