Genetic variations of the insulin receptor gene in five Taiwanese patients with syndromes of insulin resistance were investigated. The coding sequences of the insulin receptor gene were amplified and examined by DNA sequencing. A number of polymorphisms were identified, including novel Ala 815 and Ser 895. By PCR and restriction analysis of a normal population, all the polymorphisms examined were in Hardy-Weinberg equilibrium. When the polymorphic haplotype among intron 7 +28A＞C, exon 8 Ala 523, intron 11 +90G＞C, and exon 17 His1058 polymorphisms were examined, linkage disequilibrium between +28A＞C and Ala523 polymorphisms were observed. Since no mutations were identified, the results suggest that mutations at the insulin receptor locus are uncommon in Taiwanese patients with features of severe insulin resistance, dysmorphic facies and acanthosis nigricans.