L Lately, mesenchymal stem cells (MSCs) are often associated with cancer along with increasing reports of their ability to be recruited not only to tissue injury, but also to the location of the cancer. MSCs are known to produce products called secretome that can induce apoptosis of cancer cells. However, there are also studies that report the effect of cancer cell growth in its interaction with MSCs. The molecular mechanisms of how MSCs secretome influences cancer cells’ microenvironment are still poorly known, that as to whether MSCs inhibit or induce apoptosis of cancer cells remains a controversy. Therefore, further research is needed to evaluate the role secretome in inducing apoptosis of cancer cells. This research observed the ability of human umbilical cord blood (hUCB) MSCs in inducing apoptosis of HeLa cancer cells. HeLa cells were cultured and treated with several concentrations of hUCB-MSCs secretome collected in conditioned media (CM): 0% (negative control), 0.2%, 2%, and 20% and a positive control H2O2 in two different time spans of 24 hours and 48 hours. Trypan blue staining was used to count and differentiate cells living and the dead. Sub-G1 analysis with Propidium Iodide staining was used to detect apoptopic cells. The data obtained showed hUCB-MSCs secretome induced apoptosis of cancer cells HeLa. hUCB-MSCs secretome induced apoptosis starting at 0.2% of hUCB-MSC secretome in 24 hour time (p<0.05). There was an interraction between the number of apoptotic HeLa cells with concentrations and long exposure time of secretome (p=0.000*<0.05). The higher the concentration of a given secretome and the longer the exposure time, more number of HeLa cells underwent apoptosis. In addition, it was found that the hUCB-MSCs secretome also caused partial proliferation inhibition of HeLa cells.