There are disclosed apparatus and methods for treating tissue by delivering at least one therapeutic agent into the tissue. In one embodiment, the apparatus comprises a catheter and a balloon member disposed on a distal region of the catheter. A plurality of pockets are disposed on the balloon member, and a plurality of needles are associated with each of the plurality of pockets. The plurality of needles are configured to engage tissue when the balloon is in the inflated state, and further are configured to disperse a therapeutic agent from an associated pocket into the tissue when the balloon is in the inflated state. A first needle of the plurality of needles may comprise a length that is different than a second needle, permitting the delivery of first and second therapeutic agents to different depths within the tissue.