BACKGROUND Laparoscopic adrenalectomy is acknowledged as a standard procedure in adrenal lesions management. This retrospective study of lateral transabdominal laparoscopic adrenalectomy performed between 1997 and 2017 in a single center in Poland aimed to determine the factors associated with surgery time. MATERIAL AND METHODS This retrospective study involved 881 patients. The factors identified as potentially affecting surgery time were age, sex, side of the lesion, histopathological type, hormonal activity, size of the lesion, history of previous abdominal operations, presence of intra-abdominal adhesions, and obesity. The following statistical tests were conducted: t test, Mann-Whitney U test, Kruskal-Wallis H test, Pearson correlation test, and multivariate regression modeling. RESULTS The mean surgery time for all operations was 139 min (55-320 min). We observed statistically significant differences for surgery time in the following groups: sex, side of the lesion, presence of intra-abdominal adhesions, obesity, histopathological type, and hormonal activity (P<0.05). The multivariate regression model showed factors affecting surgery time were: sex, side of the lesion, size of the lesion, obesity, histopathological type (nodular hyperplasia and adenoma), and hormonal activity (non-functioning and aldosterone-secreting tumors) (P<0.05). There was no correlation between surgery time and patient age and tumor size (P<0.05). Mean tumor size was 42 mm (6-130 mm). CONCLUSIONS The 20-year experience of laparoscopic adrenalectomy performed at a single center showed that surgery duration was significantly longer in male patients, obese patients, left-sided adrenal tumors, tumors >6 cm in diameter, patients with a diagnosis of pheochromocytoma, and when intra-abdominal adhesions were present.