Adrenalectomy is the most appropriate treatment for unilateral adrenal tumors. This study aimed at describing the epidemiological characteristics and perioperative behavior of canine patients submitted to adrenalectomy at Anhembi Morumbi Veterinary Hospital. Out of 13 dogs, eight were pure breeds and five were mixed breeds; 12 females, aged 9.5 ± 2.5 years old. Regarding the tumors, seven were located on the right and histopathological analysis revealed cortical adenoma in 11 and adenocarcinoma in only two dogs. Two cases had hypercortisolism recurrence associated with hyperplasia in the contralateral adrenal, as confirmed by ACTH stimulation test. The results of this study indicate that adrenalectomy is a safe procedure with few perioperative complications, despite the possibility of hypercortisolism recurrence.