Detailed clinical histories and cytogenetic investigations using short-term cultures are reported in three typical benign lipomas. Although a diploid (normal) karyotype was observed in two cases, a reciprocal chromosome translocation t(3;12)(q28;q14) was found in the third case, which was briefly reported previously. These data are discussed in light of a lipoma with similar karyotypic changes reported by Heim et al. and a similar translocation observed by us in malignant myxoid liposarcomas. The nonrandom involvement of segment 12q13-q14 in benign and malignant lipomatous tumors suggest a common basis for at least one of the possible multiple steps in the genesis of neoplastic processes.