Adrenal tumors can be primary or secondary entities. Primary tumors are able to secrete hormones which may cause significant effects clinically. Typical tumor-related adrenal diseases are Conn's syndrome (hyperaldosteronism), Cushing's syndrome (hypercortisolism), and pheochromocytoma (catacholamine excess). Primary adrenal tumors are rarely malignant, but adrenocortical neoplasias show a relation between tumor size and rate of malignancy. Diagnostic methods for adrenal tumors include hormone tests and imaging. The first choice of treatment is surgical removal, today preferably by minimally invasive approaches.