Background. Double pituitary adenomas are a rare entity, which requires clinical attention and a careful follow-up. Case report. A 37-year-old man presented with left-sided painful gynecomastia. He denied typical symptoms of excessive growth hormone (GH) secretion and did not show any acromegalic features. Due to low testosterone and LH levels with mild hyperprolactinaemia, the patient was referred to pituitary MR, which revealed an 11x13 mm right-sided sellar tumor. An increased IGF-1 was noted subsequently (1482 ng/mL; N 109-284 ng/mL), together with the lack of GH suppression in OGTT. Transphenoidal resection of pituitary tumor performed in 2012 led to biochemical (IGF-1 260 ng/mL, GH 0.08 ng/mL) and radiological remission of the disease. A histopathology report revealed a densely granulated somatotropic pituitary adenoma with mild nuclear atypia, expressing somatostatin receptors [sstr2A (+), sstr5 (+/-)]. Due to gradually increasing IGF-1 levels (with low, although rising, GH values ranging from 0.07 to 0.92 ng/mL) in subsequent years, OGTT was repeated in 2015, showing appropriate GH suppression. In 2016, however, acromegaly recurrence was confirmed both biochemically (increasingly high IGF-1 - 664 ng/mL - and unsuppressed post-OGTT growth hormone) and in MR imaging. The patient was reoperated in June 2017. The second histopathology reported an oncocytic somatotropic acidophil stem cell pituitary adenoma with Ki-67 >3% and mitotic figures. Subsequent anterior pituitary lobe insufficiency (adrenal, thyroid and gonadal axis) was found and adequately treated. Complete tumor removal was confirmed by MR performed three months after repeated surgery, as well as a low GH level (0.97 ng/mL), although accompanied by borderline IGF-1 values (277 ng/mL). Eighteen months after surgery, the recurrence of acromegaly was again confirmed, with adenoma regrowth and increased GH (2.31 ng/mL) and IGF-1 (474 ng/mL) levels. Octreotide LAR was started (despite retina wrinkling which was observed when lanreotide was administered before the first surgery), which led to a normalization of GH (0.96 ng/mL) and IGF-1 levels (152 ng/mL), as well as partial pituitary tumor regression after six months therapy. Conclusion. In a case of GH-secreting pituitary adenoma recurrence after apparent successful surgery, a double pituitary tumor with more aggressive histology should be considered.