Neuron-specific enolase (NSE) is present in many types of peptide-secreting neuroendocrine cells and in tumours derived from them, but little work has been done on the pituitary gland. Serial sections of normal rat (n = 9) and human (n = 7) pituitary gland, spontaneous rat pituitary tumours (n = 14) and human pituitary tumours, both hormonally active (n = 7) and inactive (n = 10), were immunostained for NSE and the 6 major anterior pituitary hormones. The neural lobe stained strongly and the intermediate lobe variably for NSE. In the anterior lobe, NSE immunoreactivity was present with variable intensity in the majority of hormone-producing cells of all six types. Cells with strong hormone immunoreactivity were usually only moderately stained for NSE. All the human and rat pituitary adenomas examined were positively stained for NSE, though to varying degrees. The pituitary gland is thus no exception to the rule that NSE is found in peptide-secreting neuroendocrine cells and their tumours.