This multicentre national study has provided demographic and outcome data on over 1700 patients with rare systemic/vascular diseases as a cause of ESRD. Except for those with Henoch-Schönlein purpura, polyarteritis nodosa and Wegener's granulomatosis, women predominated. On the other hand, black patients seem less susceptible to these illnesses than white patients except for SLE. Recovery of renal function sufficient for dialysis to be discontinued was more likely in each of these diseases except for SLE than for any of the other 'rare' diseases described by us, the usual causes of renal failure as reported by the EDTA Registry or our control patients. Overall survival was quite good except in those patients with progressive systemic sclerosis whose outlook was poor.