Adrenal incidentalomas are increasingly diagnosed due to a rise in abdominal imaging. Therefore, a dedicated European Society of Endocrinology guideline was written in 2016 and recently updated in 2023. A multidisciplinary assessment of these incidentalomas should be carried out if malignancy or hormonal secretion are suspected. Up to 10% of incidentalomas are malignant. The most important imaging method for assessing dignity is computed tomography without contrast medium as homogeneity and Hounsfield units (HU) can be ideally assessed. Approximately 50% of all adrenal adenomas are characterized by mild autonomous cortisol secretion. Therefore, a 1 mg dexamethasone suppression test should be performed in all cases. Further biochemical testing (exclusion of pheochromocytoma, aldosterone-renin ratio, steroid profiling) is recommended in selected cases. An incidentaloma that is hormonally inactive and clearly benign on imaging does not require treatment or further follow-up. If malignancy is suspected, an adrenalectomy should be performed. Adrenalectomy should be performed minimally invasively if the mass is <= 6 cm and non-invasive; otherwise, open surgery must be performed. Further imaging with CT or MRI after 6-12 months should be conducted for all intermediate cases. If there is a significant growth of more than 20%, immediate surgery should be performed. Further biochemical testing should only be considered if there is a worsening or new clinical symptoms. There is a particular need for research in the treatment of adrenal incidentalomas with mild autonomous cortisol secretion, as there is currently a lack of studies for evidence-based recommendations.