Neuropeptide Y increases blood pressure and appetite, disorders of which have a genetic component. The present study examined the neuropeptide-Y Y1 receptor gene (NPYY1R) for involvement in essential hypertension (HT) and obesity. Frequency of alleles of the only known variant, involving a point mutation in intron 1, was determined by PCR and PstI digestion. Minor allele frequency was 0.37 in 75 HT offspring of two HT parents, compared with 0.35 in 86 normotensives (NTs) ( chi 2 = 0.11; P = 0.73). In obese and lean HTs frequency was 0.40 and 0.35 (chi 2 = 0.51; P = 0.46); and was 0.38 and 0.34 in obese and lean NTs (chi 2 = 0.16; P = 0.69). In conclusion, variant(s) in linkage disequilibrium with the NPYY1R RFLP are not involved in HT or obesity.