Individuals with IgA nephropathy (IgAN) who are homozygous for the deletion (D) polymorphism of the gene for angiotensin converting enzyme (ACE) are reported to be at increased risk of progressive renal damage. Since IgAN and Henoch-Schönlein purpura with associated nephritis (HSPN) share a common aetiology, we have investigated this influence in 31 children with HSPN. The distribution of genotypes was as follows: II: 4, ID: 17 and DD: 10 patients. Median length of follow-up was 4.5 years (range 0.5-15.75 years). Severe onset with nephrotic oedema and crescent formation on renal biopsy was seen in 10 of 17 patients with ID genotype and 5 of 10 patients with DD genotype. In the ID group, 2 patients have undergone renal transplantation and 4 have persistent proteinuria 4, 7, 9 and 10 years after presentation. One patient in the DD group has been transplanted and 1 patient has proteinuria and a reduced glomerular filtration rate 5 years after initial presentation. All other patients have either made a complete recovery or have microscopic haematuria alone. These results do not support an association between disease severity and DD genotype in children with HSPN; however larger studies are required to confirm this.