As an approach to estimate the involvement of the insulin receptor gene in the etiopathogenesis of type-II diabetes mellitus we determined the distribution of the alleles of a restriction fragment length polymorphism of this gene (Bgl II-RFLP) in a group of type-II diabetics. The patients had been characterized by insulin and C-peptide values during OGTT and insulin receptor binding indices. The difference in allelic distribution to a healthy control group (10% "+"-allele in diabetics versus 18% in control persons), was not significant in chi 2-analysis.