Several topical formulations of clindamycin phosphate are currently marketed for the treatment of acne vulgaris. This 12 week, multi-centre, investigator-blind, randomised, active and placebo-controlled, parallel group study assessed the clinical efficacy and safety of clindamycin 1% gel once-a-day vs clindamycin 1% solution twice-a-day, and to demonstrate its superiority vs its vehicle alone. A total of 592 subjects were included. After 12 weeks, a 65% reduction in inflammatory lesion count was observed with both active treatments. The gel was superior to its vehicle for total and inflammatory lesion reduction, Global Assessment of Improvement, and Global Severity Grade at final visit (all p < 0.01). No difference was found between the 2 active treatments for any of the evaluated criteria. Local tolerance in each active treatment group was slightly better with clindamycin gel (1.9% of subjects) relative to 3.1% in the topical solution group. In conclusion, the new water-based gel once-a-day formulation of clindamycin 1% is an effective, safe, and convenient alternative to the twice-a-day topical solution formulation in the treatment of acne vulgaris.