The multi drug-resistant cell line MES-SA/Dx5 was derived from the human uterine sarcoma cell line MES-SA which was originally obtained from a tumour from a 56-year-old Caucasian female at the time of hysterectomy. The Dx5 variant exhibits a 100-fold resistance to doxorubicin and has a reported doubling time of 30 hours. The two additional marker chromosomes indicate clonal selection during drug selection. MES-SA/Dx-5 cells exhibit marked cross-resistance to a number of chemotherapeutic agents (including daunorubicin, dactinomycin, vincristine, taxol, colchicine) and moderate cross-resistance to mitomycin C and melphalan. Cross resistance to bleomycin, cisplatin, carmustine, 5-fluorouracil or methotrexate was not observed.