In the goat adenohypophysis, percentages of somatotrophs, mammotrophs and somatomammotrophs were compared between the lactating females and the post-lactation immunohistochemically. The pituitary weight was significantly different between the lactating females (0.65±0.10g) and the past-lactation (0.38±0.07g). Except for zona tuberalis, mammotrophs appeared at significantly larger percentage in the lactating females (26.9%) than in the post-lactation (10.1%) and conversely somatomammotrophs in the post-lactation (28.1%) than in the other (16.0%) at 5% level. The percentage of somatotrophs increased only in the caudal region of the pars distalis but immunonegative cells did not show significant differences after the cessation of lactation. From these results, it was suggested that a part of mammotrophs might transform into somatomammotrophs after cessation of lactation in the female goat adenohypophysis.