The adrenocortical function of pomeranians and miniature poodles with alopecia was tested by serial measurements of the urinary corticoid: creatinine ratio (uccr) and by an oral low-dose dexamethasone suppression test (lddst) and uccr measurements. In most of the dogs there was day-to-day variation in the uccrs of the 10 sequential urine samples, often with values above or below the upper limit of the range of healthy control dogs. In 22 alopecic pomeranians the basal uccrs were significantly higher than in 18 non-alopecic pomeranians, and the values of both groups were significantly higher than those of 88 healthy pet dogs. The uccrs of 12 alopecic miniature poodles were significantly higher than those of healthy dogs. In 12 alopecic pomeranians and eight alopecic miniature poodles the oral lddst revealed increased resistance to dexamethasone. In six non-alopecic pomeranians the uccrs after the administration of dexamethasone were not significantly different from those in seven healthy dogs at the same time. In an oral high-dose dexamethasone suppression test, using 0·1 mg dexamethasone/kg bodyweight, the uccrs of seven alopecic pomeranians and five alopecic miniature poodles decreased to low levels.