Several clinical trials are currently evaluating the safety and efficacy of mesenchymal stem cells (MSCs) in different diseases. The MSCs are guided by inflammatory mediators and specific interactions with immune cells occur, especially between MSCs and the cells of the innate immune system. At the present many of these interactions remain to be determined. This review summarizes the current knowledge in relation to the susceptibility of MSCs to NK cell mediated lysis as well as the immunomodulatory activity of MSCs and its control over NK cell function. Here we hypothesize that the inflammatory context will regulate the outcome of NK-MSC interactions.