Despite several years of intense investigation, there continues to be controversy about the value of clinical, demographic and histologic features in prediction of outcomes of lupus nephritis. In addition, contemporary treatments have reduced the risk of progressive renal injury and thus may have altered the prognostic significance of some of these factors. We have therefore re-examined the predictive value of variables previously associated with an increased risk of renal insufficiency by studying 65 patients with severe lupus nephritis treated with intensive regimens of intravenous pulse cyclophosphamide or methylprednisolone. Five clinical features at study entry were each associated with an increased probability of doubling the serum creatinine: age greater than 30 years, Black race, hematocrit less than 26%, serum creatinine greater than 2.4 mg/dl, and C3 complement less than 76 mg/dl. By multivariate survival analysis, serum creatinine, hematocrit and race emerged as the strongest set of independent clinical predictors; the other clinical and demographic factors, including age and C3 complement did not contribute significantly to outcome predictions in the context of these three variables. Renal biopsy evaluation offered additional prognostic information and showed that patients with severe active and chronic histologic changes were at increased risk for developing renal insufficiency. The combination of cellular crescents and interstitial fibrosis was particularly ominous. Outcome predictions based on the strongest clinical model (serum creatinine, hematocrit and race) were significantly enhanced by the addition of renal pathology data. Consideration of these prognostic factors may contribute to decisions regarding the type and intensity of immunosuppressive therapy for patients with lupus nephritis.