Since its clinical delineation, the premenstrual syndrome has enjoyed a wide repertoire of descriptive labels commensurate with the enormity of its symptomatology and the diversity of its postulated aetiologies, none of which has attained pre-eminence, although some (e.g. progesterone deficiency) have been of more enduring interest, due perhaps as much to the enthusiasm of their authors as to the presence of any compelling scientific premise. The entity thus remains of syndromal status constituting as it does an enigmatic curiosity for some and a fellowship of controversy for others, with little agreement as to its exact nature, time of occurrence or even its existence.