Objective: To study the effect of botulinum toxin A in the subscapular muscle on shoulder pain and humerus external rotation. Methods: 22 stroke patients with spastic hemiplegia, substantial shoulder pain and reduced external rotation of the humerus participated in a randomised, double blind, placebo controlled effect study. Injections of either botulinum toxin A (Botox, 2 x 50 units) or placebo were applied to the subscapular muscle at two locations. Pain was scored on a 100 mm vertical Visual Analogue Scale; external rotation was recorded by means of electronic goniometry. Assessments were carried out at 0 (baseline), 6 and 12 weeks. Results: 21 patients completed the study. We observed no significant changes in pain or external rotation as a result of administration of botulinum toxin A. External rotation improved significantly (p = 0.001) for both the treatment group (20.4° (16.6) to 32.1° (14.0)) and the control group (10.3° (19.5) to 23.7° (20.7)) as a function of time. Conclusions: Application of botulinum toxin A into the subscapular muscle for reduction of shoulder pain and improvement of humeral external rotation in spastic hemiplegia does not appear to be clinically efficacious.