OBJECTIVE To report the descriptive epidemiology of acetabular labral enlargement and analyze associations of other variables with this variant. METHODS Pelvis radiographs from 761 Pima Indians aged > or = 45 years enrolled in a population based study were read by Kellgren-Lawrence global and individual radiographic features grading scales for osteoarthritis (OA) at separate settings. In total, 722 radiographs remained eligible for this study after excluding 12 unreadable radiographs and 27 cases of radiographic hip OA (Kellgren-Lawrence grade > or = 2). Enlarged acetabular labra were recorded during readings of individual radiographic features. RESULTS Enlarged acetabular labra were present in 16% of study participants without OA and were significantly associated with female sex, but not with the variables age, body mass index, clinical hip joint involvement, diabetes, or serum insulin concentrations. CONCLUSIONS Acetabular labral enlargement is common in the Pima Indians, and although not in excess of other reported acetabular margin anomalies, it differs in appearance and is not associated with age. Recognition of this structural variant is important because it can mimic fractures or osteophytes.