All rights reserved. Presently multicellular tumor spheroids (MTS) are being widely used in various aspects of, tumor biology, including studies in biology and photodynamic therapy. The cellular organization of, spheroids allows the recreation of in vivo small tumors much better than all common two-dimensional in vitro models. The cell encapsulation method could be proposed as a novel technique to quickly and easily prepare a large number of spheroids with narrow ste distribution within a desirable diameter range. Moreover, the proposed technique for spheroid generation using encapsulated growing tumor cells could provide entirely new avenues to develop a novel spheroid co-culture model (for instance, the in vitro co-cultvation of tumor cells and monocytes, or epithelial cells, or fibroblasts etc). The current research was aimed at developing a simple and reliable method to encapsulate tumor cells and to cultivate them in vitro. In order to generate spheroids, MCF-7 cells were encapsulated and cultivated in 200 ml Tr-flasks in a 5% CO2 atmosphere at 37°C for 4-5 weeks. The cell proliferation was easily observed using a light microscope The cells arew in aaareaates increasina in size with time The cell growth resulted in the formation of large cell clusters (spheroids) which filled the whole microcapsule volume in 4-5 weeks.