The sensitivity and percent agreement of 3 methods of classifying patients with systemic lupus erythematosus (SLE), the 1982 American Rheumatism Association (ARA) revised criteria and a simple and full classification tree, were compared using data from The Johns Hopkins Lupus Cohort, a prospective study of 198 patients with SLE. The 1982 revised criteria were significantly more sensitive than the simple classification tree, correctly identifying 184 (93%) cases compared to 168 (85%) (p = 0.016). Agreement between these 2 classification schema was noted in 174 (87%) cases with 164 classified correctly and 10 failing to satisfy either criteria set. The full classification tree correctly identified 186 (94%) cases. There was no difference in the sensitivity of either the 1982 revised criteria or the full classification tree by racial group; however, the simple classification tree was significantly less sensitive among black than Caucasian patients (80 vs 91.5% p = 0.038). Our data support the continued use of the 1982 revised ARA criteria for the classification of patients with SLE for clinical and epidemiologic research studies.