In 17 patients, active (diffuse) lupus glomerulonephritis was treated with a combination of mechlorethamine (HN<sub>2</sub>) and a high dose of corticosteroids (HDS). Serial clinical and sequential histologic observations were made. The results were compared with those from a previously reported and comparable group of patients who were treated with HDS alone. The mortality rate seen in the more severely affected patients was similar in both groups and there was no significant difference in estimated survival. By contrast, in those in whom the kidneys were less severely affected, the estimated survival appeared to be better in those treated with HDS-HN<sub>2</sub>. Control of histologic activity also occurred more rapidly in the HDS-HN<sub>2</sub> group.