36 consecutive patients whose biopsies showed significant extracapillary proliferation in the face of rapidly declining renal function were reviewed between 1967 and 1979. About 30% of the patients belonged to the pediatric age group with a male:female ratio of 2.5:1. Oliguria/anuria, hematuria, and progressive renal insufficiency were present in all cases. There was evidence of 9 cases being poststreptococcal, 2 SLE, 1 Henoch-Schönlein purpura, 2 possibly viral and 1 staphylococcal. Histologically, 29 cases had more than 60% crescents, 5 between 50 and 60% and 2 cases a little less than 50%. 28 cases were fatal in less than 10 months. 2 were lost of follow-up. 6 survivors with reversal of renal functions had 3 common factors to note, namely an antecedent disease, less crescents both in number and size, accompanied by fewer interstitial changes and early treatment. Rebiopsy in 2 survivors showed regression of histologic severity.