Background: Mesenchymal stem cell conditioned media (MSCs-CM) is derived from MSC culture and contains the majority of the potential cytokines secreted by MSCs. Ehrlich ascites carcinoma (EAC), a transplantable neoplasia derived from a malignant epithelium, causes ascites when it is injected into the intraperitoneal cavity. Aim: the present study revealed antitumor potential of MSCs-CM from different sources on experimental animals tumor model (EAC) in vivo and on cancer cell line (MCF-7) in vitro Material and methods: Sixty female mice were divided into 6 groups (n=10) all groups except group 1 received EAC cells (1×10 ⁶⁾. Group 1 negative control group, group 2: positive EAC control group, group 3: MTX treated group. Group 4: adipose MSCS-CM treated group, group 5: liver MSCs-CM treated group and group 6: bone marrow treated group. At the end of the experiment:  liver, kidney tissues and ascites fluid were collected. Results: Treatment with MSCs-CM showed a significant decrease in tumor cell count and reduced in ascites volume moreover a significant decrease in malondialdhyde levels compared to positive EAC group (p<0.001) while a significant increase in levels of total antioxidant capacity had been detected compared to EAC group (p<0.001). Whereas in human breast cell line (MCF-7), marked induction of apoptosis was observed.  Conclusion: MSCs-CM has antitumor activity in vivo and in vitro.