Fifty cases of SLE have been collected over a ten year period and the incidence and clinical picture of LN reviewed in the light of other published data. Lupus nephritis, like SLE, has a variable pattern of its own with a wide spectrum of renal involvement–evaluation of therapy and prognosis will have to be conducted against this background. Lupus nephritis may present as a renal syndrome only, without any of the other manifestations of SLE. Renal involvement in SLE is common, but this does not necessarily indicate a poor short-term prognosis. In the Peter Bent Brigham Hospital series a sustained raised blood pressure and the onset of renal insufficiency influenced the prognosis adversely.