Purpose <p>The aim of this prospective longitudinal study was to evaluate cognitive function and fatigue before and 12 months after transsphenoidal surgery (TSS) for a pituitary adenoma.</p> Methods <p>This study was part of the Gothenburg Pituitary Tumour Study, which consecutively includes patients undergoing TSS at Sahlgrenska University Hospital. Adult patients with a pituitary adenoma were recruited between October 2016 and May 2021. Cognitive function and fatigue were evaluated using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and the Multidimensional Fatigue Inventory (MFI-20). Paired comparisons were made for total and subscale scores before and after TSS. Based on normative data, individual scores were classified into one of three categories for symptom severity (normal, moderate, or severe) before and after TSS.</p> Results <p>Fifty-nine patients (31 females) were included. Among them, 42 had non-functioning pituitary adenomas (NFPA) and 17 had a functioning pituitary adenoma. There were no differences in RBANS total or domain indices before and 12 months after surgery except for the attention index which improved. Total MFI-20 and all subscale scores improved. The improvement was more pronounced in patients with functioning pituitary adenoma, who reported worse fatigue before surgery compared to patients with NFPA. Individual differences between pre- and postoperative scores that also changed category of symptom severity were seen for 37% of all patients regarding cognition and for 35% regarding fatigue. Improvements accounted for the majority of these changes.</p> Conclusion <p>Cognitive function remained largely unchanged from before to 12 months after TSS, while self-reported fatigue improved.</p>