In briefPhysicians perform a delicate balancing act when they weigh a patient's medical condition against the safety of sports participation. This article, the second of a two-part series on contraindications to activity, examines the sensory, spinal, gastrointestinal, systemic, hematologic, and dermatologie conditions that warrant activity disqualification and provides guidelines about when it's safe to participate. Also discussed are activity considerations for patients who have lost a paired organ.