Background: Spasticity is a disabling complication of multiple sclerosis, affecting many patients with the condition. We report the first Phase 3 placebo-controlled study of an oral antispasticity agent to use an enriched study design. Methods: A 19-week follow-up, multicentre, double-blind, randomized, placebo-controlled, parallel-group study in subjects with multiple sclerosis spasticity not fully relieved with current antispasticity therapy, Subjects were treated with nabiximols, as add-on therapy, in a single-blind manner for 4 weeks, after which those achieving an improvement in spasticity of 20% progressed to a 12-week randomized, placebo controlled phase. Results: Of the 572 subjects enrolled, 272 achieved a 20% improvement after 4 weeks...