Pituitary adenomas, even after successful treatment, are associated with cognitive impairments. It is unclear whether these deficits are a consequence of unspecific factors associated with having a chronic illness and whether the cognitive dysfunctions exceed those of other chronically ill patients. Thirty-eight patients with transsphenoidal surgery for pituitary adenomas and 38 patients undergoing L-thyroxine replacement therapy after thyroid surgery were studied neuropsychologically with established tests. Executive function was examined with the Trail-Making Test A and B, working memory with the digit span test, attention with the digit symbol test, verbal memory with the German version of the Auditory Verbal Learning and Memory Test, and general verbal intelligence by a vocabulary test. Attention (p = .007), attentional speed (p = .0004), executive control (p = .04), and working memory (p = .01), were significantly reduced in patients with pituitary adenomas compared with other chronically ill patients. In contrast, no differences were found between the groups for verbal memory (all subtests: p ≥ .06). Patients with successful surgery for pituitary adenomas show also in comparison with other chronically ill patients an increased risk for deficits in certain aspects of cognitive function, including attention and working memory, supporting the relevance of the brain lesion and its treatment for these dysfunctions.