Objective: To evaluate the efficacy and safety of a homeopathic arnica gel (Arnicare?) in the treatment of sports related muscular soreness and pain. Design: Randomized, double blind, placebo controlled clinical trial Setting: Self use of an over-the-counter preparation by athletes participating in a club sport activity. Subjects: Moderately trained athletes who experienced pain and stiffness after competitive sports games. Interventions: Arnicare?, a homeopathic gel containing 7% arnica montana 1X, or matching placebo, applied to the lower extremities 3 times daily shortly before and after sports games until resolution of symptoms. Main outcome measures: Pain and stiffness at different time points as assessed on a 100mm visual analogue scale after in total three sports games. Results: 120 subjects (54 males, 66 females) were enrolled and randomized into two groups of 60. Subjects were mainly basketball players (85%) and the groups were comparable at baseline. The overall (baseline adjusted) level of stiffness during the 72 hours following the sports game was significantly less in the Arnicare group as compared to the placebo group (23.7mm versus 29.1mm, P=0.02). With regard to the overall level of pain there was a similar trend that did not reach statistical significance (24.9mm versus 27.9mm, P=0.17). Between group differences were most pronounced 12-36 hours post-exercise. 2 subjects in the arnica group experienced mild side effects (slight tingling, itching) that did not lead to discontinuation of the treatment. Conclusions: Arnicare? gel can be used after sports activities to help with the short term effects of exercise stiffness and pain, as a substitute for OTC analgesic and anti-inflammatory drugs: very few subjects used any analgesic in conjunction with Arnicare? gel. Furthermore, Arnicare? gel was safe in use.