Finding genes that cause human hypertension is not straightforward, since the determinants of blood pressure in primary hypertension are multifactorial. One approach to identifying relevant genes is to elucidate rare forms of monogenic hypertension. A relevant mutation may provide a rational starting point from which to analyse the pathophysiology of a condition affecting 20% of the world's population. In 1973 a family with autosomal dominantly inherited brachydactyly and severe hypertension, where the two traits cosegregated completely, was described. We have now re-examined this kindred, and localized the hypertension and brachydactyly locus to chromosome 12p in a region defined by markers D12S364 and D12S87. As the renin-angiotensin-system and sympathetic nervous system respond normally in this form of hypertension, the condition resembles essential hypertension. This feature distinguishes this form of hypertension from glucocorticoid remediable aldosteronism and Liddle's syndrome, which are salt-sensitive forms of monogenic hypertension with very low plasma renin activity. We suggest that identification of the gene involved in hypertension and brachydactyly and its mutation will be of great relevance in elucidating new mechanisms leading to blood pressure elevation.