Multiple Endocrine Neoplasia type 1 (MEN 1) is an autosomal dominant syndrome characterized by neoplasia of the parathyroid glands, the endocrine pancreas and the anterior pituitary gland. Recently the identification on chromosome 11 (locus q13) of the gene responsible for MEN 1 has allowed direct genetic diagnosis of MEN 1-affected family members. To date almost 300 families have been described and genetically characterized. The genetic etiology of most pituitary tumours remains unknown. Pituitary adenomas can develop sporadically or as a part of multiple endocrine neoplasia type 1. In this review, the recently published data on the pathology of the MEN 1 syndrome will be summarized. The clinical, morphological and genetic aspects of sporadic and MEN 1-associated pituitary adenomas will be outlined.