In-line skating injuries have increased in recent years. Hospital based data from Umeå concerning 135 persons injured in in line skating collisions were analyzed. The highest yearly incidence of injury was found in males 10-19 years of age, at 1.7 per 1,000 inhabitants; the corresponding figure for females was 0.5. Two-thirds of incidents were caused by falls due to balance problems without the influence of any "external factor" such as rough road surfaces. No collisions with motor vehicles or other road users were registered. Nearly half of the injuries were fractures or dislocation injuries, most frequently of the upper extremities. Non-minor head injuries were rare. Protective gear for wrist and elbow may have the potential to reduce these injuries.