Based on 880 pituitary adenomas operated upon between 1972 and 1982 the diagnostic and therapeutical strategy in recurrences is discussed. The incidence of reoperations was 7.75%, 3.7% in hormonally inactive and 4.1% in hormonally active recurrences. The rate was 30% after transcranial surgery--due to the extension of the tumours--and 5% after the trans-sphenoidal approach. In hormone inactive adenomas visual impairment in 29 out of 50 recurrences caused a second operation combined with radiotherapy in 13 cases. Radiotherapy alone was used in 17 cases. In hormonally active adenomas the treatment of persistent hormonal excess represents the main therapeutical problem. With HGH-producing adenomas a return to normal was achieved in 22 cases mainly by a combination of reoperation and radiotherapy (12) or radiotherapy (8) alone. Radiotherapy should be avoided in young patients whenever possible. The procedure of choice in PRL-producing adenomas (14 cases) seems to be treatment with dopamine-agonists (9). An additional reoperation was necessary in five cases.