The Nipple is a specialized structure which can be erected by various stimulations and provides induction of milk ejection reflex and sexual arousal due to its intense sensory innervation. Smooth muscles in its structure have been found to be related with the nipple erection mechanism. However, studies aimed at explaining nipple erection mechanism are insufficient. Smooth muscle morphology were investigated by Masson’s trichrome staining on sagittal sections performed in 17 different human nipple-areola complex (NAC) samples. According to the results, NAC smooth muscles that have longitudinal and horizontal course are associated with epidermis, lactiferous ducts and blood vessels. Besides, areola is richer compared to nipples in terms of horizontal muscle fibers. Despite being erectile textured, NAC are different from penis in its structure. Contrary to available data, when the NAC smooth muscle morphology evaluated together with erection dynamics, smooth muscle relaxation should also be considered to have an effect.