The clinical, therapeutic, and laboratory aspects of pituitary tumors are outlined. Sometimes tumor symptoms like headaches and visual disturbances are not present, while endocrine symptoms depend on the type of trophic cells involved: acromegaly for growth hormone, Cushing syndrome for cortico-melanotrophic hormone, amenorrhea-galactorrhea for prolactin, and rarely, symptoms related to thyrotropin or gonadotropin. Recently prolactin-secreting adenomas have been differentiated from chromophobic adenomas in routine diagnosis. The endocrine symptoms may be masked by estrogen-progestagen pills until tumor symptoms develop, when surgery is mandatory. The results of surgery depend on the tumor volume. Selective adenectomy usually permits normal endocrine function afterward. These tumors may also be treated pharmacologically, e.g., with L-DOPA or dibromoergocryptine. The results of treatment are followed by pre- and postoperative radioimmunoassay of pituitary hormones.