In order to compare the clinical presentation of overuse injuries in older and younger athletes, retrospective patient chart data were obtained from cases which had been referred to an outpatient sports medicine clinic over a 5-yr period. A total of 1,407 cases were studied comprising two populations separated by significantly (P less than 0.001) different ages: 685 "old" (mean age = 56.9 +/- 6.1 yr) and 722 "young" (mean age = 30.4 +/- 8.1 yr). Although the two subpopulations demonstrated modest differences in sport activity at the time of injury, specific diagnoses, and anatomic location of injury, many similarities existed between the groups. Running, fitness classes, and field sports were more commonly associated with injury in the younger group, while racquet sports, walking, and low intensity sports were more commonly associated with injury in the older group. The frequency of tendinitis was similar in both age groups, while metatarsalgia, plantar fasciitis, and meniscal injury were more common in the older population, and patellofemoral pain syndrome (PFPS) and stress fracture/periostitis were more common in the younger population. Anatomically, injury sites in the foot were more frequent in the older group, while injury sites in the knee were more frequent in the younger group. In the older population, the prevalence of osteoarthritis was 2.5 times higher than the frequency of osteoarthritis as the source of activity-related pain. In the older group, 85% of the diagnoses were overuse injuries known to respond to conservative treatment, 14.4% of the cases required consultative referral, and only 4.1% required surgery.