The aim of this study was to test the hypothesis that HLA-DRB1, -DQA1, and -DQB1 subgroups or angiotensin-converting enzyme (ACE) gene polymorphisms are associated with severe retinopathy in younger Type 1 diabetic patients. Twenty-four Type 1 diabetic patients who had received panretinal photocoagulation for severe nonproliferative or proliferative diabetic retinopathy were compared with 24 Type 1 diabetic patients (participating in a photographic screening program with regular fundus examinations) with no or minimal retinopathy, matched for age at onset and duration of diabetes. The HLA-DRB1-DQA1-B1 haplotype 04-03-0302 represented 22/48 (46%) in the severe and 21/48 (44%) in the no/minimal retinopathy group, respectively (n.s.). The most common genotype, 03-0501-0201/04-03-0302, occurred in 8/24 (33%) with severe and 10/24 (42%) with no/minimal retinopathy, respectively (n.s.). There were no statistical differences between patients with severe and no/minimal retinopathy whether DRB1, DQA1, or DQB1 alleles, haplotypes, or genotypes were analysed. The ACE gene polymorphism was almost identical between patients with severe and no/minimal retinopathy, and serum ACE levels did not differ. Thus, in the present study on a small group with carefully characterised diabetic retinopathy phenotypes, there was no indication that HLA-DRB1, -DQA1, and -DQB1 subtypes or ACE gene polymorphisms were associated with severe retinopathy in younger Type 1 diabetic patients.