The authors analysed the incidence of renal diseases as diagnosed by biopsy in the population living on the southern Great Hungarian Plain. 798 biopsy specimens were examined between 1990 and 2002.The most common diseases in decreasing order of frequency were IgA nephropathy (15%), membranous nephropathy (12%), thin-basement-membrane nephropathy (8%), minimal change nephropathy (7%), lupus glomerulonephritis (7%), focal sclerosis (6%), hypertensive kidney disease and arteriolosclerosis (5%), diabetic nephropathy (5%), and crescentic glomerulonephritis (4%). The most frequent diseases in decreasing order of frequency in children were minimal change nephropathy, thin-basement-membrane nephropathy, Henoch-Schönlein nephropathy and IgA nephropathy; in adults were IgA nephropathy, membranous nephropathy, lupus glomerulonephritis and thin-basement-membrane nephropathy; and in the elderly were membranous nephropathy, amyloidosis, crescentic glomerulonephritis and diabetic nephropathy. The incidence of the diseases differed significantly between the genders in IgA nephropathy, thin-basement-membrane nephropathy, lupus glomerulonephritis, chronic sclerosing nephropathy and Alport nephropathy. At the time of the biopsy, 69 patients were suffering from diabetes mellitus. 37 patients were diagnosed as having diabetic nephropathy, and 32 as having non-diabetic nephropathy. In 6 cases, the diabetic nephropathy was accompanied by other glomerular disorders. In more than half of the diabetic patients with non-diabetic nephropathy, membranous nephropathy or focal sclerosis was diagnosed. Crescentic glomerulonephritis was diagnosed on 30 occasions, which was due to vasculitis in 20 cases, proliferative glomerulonephritis in 7 cases and anti-glomerular-basement-membrane nephritis in 3 cases. In the middle-aged and the elderly, the renal disease was relatively often a consequence of systemic disease.The incidence and the gender distribution of renal diseases diagnosed by biopsy were similar to those reported by other European kidney biopsy centres. IgA nephropathy was the most frequent disease in the biopsy registry of the authors. The high incidence of thin-basement-membrane nephropathy seems to be related to consequent biopsy examinations of glomerular haematuria. In diabetics and the elderly, the diagnosis of the renal disease may be challenging.