Between 1970 and 1984, the diagnosis of glomerulonephritis was made in 860 patients on the basis of a nephritic sediment and/or renal biopsy; of these patients, 86 (10%) had at least one first-degree relative with glomerulonephritis. These patients originated from 45 families and 1674 family members were screened; 172 had glomerulonephritis, of whom 101 could be classified. The diagnostic breakdown of the 101 patients showed that 50.5% had classical Alport's syndrome; 21.8% had atypical forms; 17.8% had familial IgA glomerulonephritis; 1.9% had focal segmental glomerulosclerosis with Wolff-Parkinson-White syndrome; and 7.9% had benign familial haematuria. The proportion of patients with glomerulonephritis who had familial disease was higher than expected. The family history is an important point to consider in the examination of patients with glomerulonephritis.