To investigate sonographic features and evolution of breast fat nodules after cosmetic augmentation with autologous fat. Breast sonography was performed on 41 patients who underwent bilateral breast augmentation by autologous fat injection. Sonography was initiated 2 to 17 months after the operation. Follow-up sonography evaluated the size, positions, shape, echogenicity, margin features, calcifications, and evolutions of the suspicious nodules in the breasts. We visualized 118 nodules in 34 of the 41 patients after the fat graft. Echotextures in 118 nodules were cystic (73, 61.9%), complex (19, 16.1%), or solid (26, 22%). We observed that 86 of the 118 nodules (72.9%) had circumscribed margins, 94 nodules (79.7%) had regular shapes, 9 nodules (7.6%) had egg-like calcifications, and 106 nodules (98.3%) had no halo. All nodules lacked blood flow signal on color or spectral Doppler. Changes in nodule echotexture were observed during the follow-up. Four nodules changed from solid to complex, one nodule changed from solid to cystic, and one complex nodule exhibited an increased cystic component. The size of the nodules decreased in 13 cases and increased in 20 cases. There were 7 nodules with fat necrosis, which was removed surgically and confirmed by pathology. Breast ultrasound, an accurate and simple imaging technique, plays an important role in follow-up for temporal changes of fat nodules after autologous fat injection. Furthermore, breast ultrasound may avoid unnecessary biopsies.