Either thyroidectomy or hypophysectomy is followed by an increase in plasma hexosamine level which is higher and more sustained than that following a sham operation. Plasma hexosamine levels increase to the same degree in response to the stress of sham operation, adrenalectomy, and castration. There are no significant changes in relative plasma volume (ml/100 g. body weight) 18 days following thyroidectomy, whereas sham-operated control rats demonstrate a relative decrease in plasma volume with growth.