Four cases of growth-hormone-secreting pituitary adenoma, with associated aspects of acromegaly and gigantism, are reported in patients aged 12-26. All of the patients had macroadenomas and were treated surgically, three by the transsphenoidal approach and one with a transfrontal craniotomy. Histologic examination revealed eosinophilic adenomas in three of the cases and a mixed eosinophilic--chromophobe adenoma in one, all with cellular irregularities (mitosis and cellular and nuclear polymorphism), local invasivity, or both. Because surgical treatment did not produce complete normalization of growth hormone levels, radiotherapy followed the operations in all four cases. In our opinion, the treatment of acromegalic gigantism poses more therapeutic problems than that of simple acromegaly, with combined treatment (surgical, radiation, and medical) often being necessary.