A drive bracket assembly (10) includes a bracket (40) adapted for receiving a disk drive (50) therein, a rail (30), and a retaining piece (20). The bracket includes first and second sidewalls (41, 45), and a plurality of slots (42) is defined in the first sidewall. The rail is adapted for being attached to one side of the disk drive. A protrusion (36) protrudes outwardly from the rail. A pair of poles (32) is outwardly formed from the rail, for sliding in a select one of the slots of the first sidewall. The retaining piece is attached to the first sidewall. The retaining piece includes a handle portion (22) and a resilient clip (23) engaging with the protrusion of the rail, thereby securely retaining the disk drive in the bracket. When the handle portion is pressed toward the first sidewall, the clip is rotated outwardly thereby releasing the protrusion.