Kallmann syndrome is an inherited disease which is characterised by anosmia (inability to smell) and hypogonadotropic hypogonadism both of which are thought to occur as a result of a failure of correct neuronal migration. To date the only genetic lesions identified are mutations in the X-linked gene, KAL. We conducted a mutation screen of the KAL gene in a family with Kallmann syndrome. This identified a new mutation in the KAL gene which removed an acceptor site at the junction of exon 6/intron 5. Exon 6 of the KAL gene encodes the C-terminal portion of a fibronectin type III domain may be involved in axonal pathfinding. We presume that the described mutation would result in the removal of exon 6 resulting in a frame shift which terminates the protein prematurely. It has been proposed that both mental illness and vesico-ureteric reflux are associated with mutations in the KAL gene. However, results from the family presented here do not show an association between either trait and the KAL gene mutation.