PURPOSE: To compare the sonographic findings of galactocele according to it's association with pregnancy. MATERIALS AND METHODS: We rev i ewed the sonographic findings of 21 lesions in 20 patients confirmed by surgery (n=15) or fine needle aspiration (n=6) as galactoceles. The patients were divided into two groups, according to the period from the most recent pregnancy or lactation. In the first group(n=8, mean age=28.6 years), this was less than one year and in the second group(n=13, mean age=45.6 years), was more than one year. RESULTS: In our study, pregnancy-unrelated galactoceles (n=13) were more common than pregnancy-related galactoceles (n=8). The sonographic findings of galactocele of the first group were as follows; ovoid anechoic cystic mass (n=5), cystic mass with fat-fluid level (n=2), and well defined heterogeneous mass (n=1). Those of the second group were as follows; irregularly bordered deeply hypoechoic mass (n=3), irregularly bordered hypoechoic mass with internal nodules (n=3), homogeneous hypoechoic mass with smooth margin (n=4), and lobulated anechoic mass with posterior acoustic enhancement and internal debris (n=3). CONCLUSION: Pregnancy-unrelated galactoceles demonstrated the variable sonographic findings of solid f mass, whereas most of pregnancy-related galactoceles demon-strated the sonographic features of cysts.