This report describes the clinical and cytogenetic analysis of a kindred with multiple endocrine neoplasia type 2 (MEN-2 or Sipple's syndrome) in two generations. Medullary thyroid carcinoma was present in five members either as a large or as an occult tumour. Phaeochromocytoma was demonstrated in one severely hypertensive relative and urine vanillylmandelic acid (VMA) was increased in one normotensive member. Serum parathormone (PTH) was normal in all but one normocalcaemic patient of this family who did not have a history of nephrolithiasis. Prometaphase banding failed to detect a 20p12.2 deletion or chromosome instability as observed in some MEN-2 families.