Introduction: Proliferative GN (WHO Type IV) is generally found in patients with severe Lupus Nephritis. Objective: To define the histopathological characteristics of renal involvement in AA patients with severe clinical Lupus Nephritis. Method: Biopsy specimens (24) from 21 AA SLE patients (19 females), were evaluated by an integrated method of High Resolution Microscopy (plastic technology), Transmission Electron Microscopy and Direct Immunofluorescence. The series consists of patients with the most severe form of clinical nephritis from a cohort of 126 AA SLE patients (121 females) seen at a large city Hospital over a period of 24 years. Results: Patients fulfilled ACR/ARA criteria for the classification of SLE. The mean±SD for age at diagnosis, and age and duration of disease at time of biopsy were 26.3±10.9, 33.9±9.1, and 7.6±7.1 years respectively. The most common manifestations were Proteinuria>1gr/24 hours in 20 pts (nephrotic range in 12 of them), and nephritic urinary sediment in 16. Hypertension was present in 13 and abnormal high serum creatinine level in 7 (range 1.3 - 4.9 mg/dl). Fifteen of 21 patients (71.4%) had Membranous GN (Type V). Crescents were seen in 7/21 (33.3%), distributed in Classes III, IV and V. (Table). WHO Class Patients Crescents WHO Class Patients Crescents 1982 n % n % I 1 4.8 0 Va 5 23.8 0 III 1 4.8 1 Vb 6 28.5 0 IV 3 14.3 3 Vd 2 9.5 1 VI 1 4.8 0 V 2 9.5 2 Conclusions: (1) Membranous Glomerulonephritis pure or associated with other classes predominates in this sample of AASLE patients. (2) One third of patients exhibited active or chronic crescents.