We analysed the distribution of genotypes and frequency of alleles of two polymorphisms in the urokinase-type plasminogen activator (uPA) gene: a C-->T substitution in exon 6 and a T-->C substitution in intron 7 in 89 children with type 1 diabetes mellitus and insulin resistance compared with 120 non-diabetic control subjects. All genotypes were determined by the allele-specific polymerase chain reaction. We found that the frequency of the T/T homozygote (15%) in the patient group was significantly (P<0.05) higher than in the controls (7%). There were no differences in the distribution of the T-->C polymorphism between patients and controls, which suggests that this genetic change is probably phenotypically silent. In conclusion, our results indicate that the higher percentage of T/T homozygotes in patients might be associated with T1DM coexisting with insulin resistance.