IgA nephropathy is the most common primary glomerulonephritis worldwide. It is also the most common cause of chronic renal failure among primary glomerulonephritides. Pathogenesis of IgA nephropathy is still obscure but new concepts about a role of immunoglobulin A oligosacharide side chains, which are under-galactosylated in these patients, háve emerged. Circulating immune complexes are composed of these aber-rantly glycosylated IgA and IgG with specificky to these oligosacharides. The samé complexes were also detected in the kidney deposits. Clinical presentation of the early stage of IgA nephropathy is characterized by asymptomatic hematuria (gross hematuria during upper respiratory infection in some patients). In later course, the progression is signalized by inereasing proteinuria and hypertension. Diagnosis of IgA nephro¬pathy is established by demonstration of predominant IgA deposits in renal biopsy. Specific therapy of IgA nephropathy is unknown but we are able to slow its progression. A restriction of protein intake correspon-ding to the degree of renal functional damage and blood pressure normalization by ACEI or ATI blockers are main non-specific therapeutic interventions. Fish-oil administration also seems to be effective while cytotoxic drugs administration is still questionable. Renal failure develops in 30 to 40 % patients 20 years after diagnosis.

        Key words: IgA nephropathy - natural history - differential diagnosis - therapy