We report on an individual with Kallman syndrome (KS) and a balanced de novo translocation (7;12)(q22,q24). None of 6 full sibs, 3 half-sibs, or parents have KS or this chromosome translocation. This is the only known report of KS with a chromosome abnormality. This may represent a spurious association or genetic heterogeneity vis-a-vis the reported linkage of KS to the steroid sulphatase gene on the X chromosome. The pathophysiology and genetics of KS are discussed.