Late hematoma formation is a rare complication of augmentation mammaplasty. Late hematoma formation related to excessive or vigorous squeezing of the breast during sexual activity has not been described. We present 2 such cases and review the English-language literature on all causes of late hematoma formation after breast augmentation reported thus far. It is suggested that this newly reported cause is probably underreported, either because of unnoticed small hematomas or because of embarrassment of the patient. Bleeding is probably caused by the rupture of vulnerable vessels in the tissue capsule, triggered by a minor or more obvious trauma. Late hematomas might be a cause of late capsular contraction in the augmented breast. Ultrasound or magnetic resonance imaging is a reliable method to confirm the diagnosis of late hematoma formation. Treatment should preferably be surgical, but in minor cases observation may be justified.