The aetiology of pregnancy induced hypertension (PIH) is unknown. Either an immunological or a genetic disorder are considered likely, with possibly an interaction between the two. If this were true, homozygosity would play an important role. Though consanguinity is believed to play a protective role, the effect of inbreeding on PIH has been inadequately studied. In South India consanguinity is common (26%). We prospectively studied 814 primigravidas of whom 213 had consanguineous marriages. The proportion of women who developed PIH was compared in the 2 groups of women with consanguineous and nonconsanguineous marriages. The odds of a patient with PIH being consanguineous was 1.12 with a 95% confidence interval of 0.72-1.75. Our observations suggest that consanguinity does not influence the incidence of PIH.