Multicellular tumour spheroids (MCTS), the best-described three-dimensional tumour model, offers an excellent in vitro screening system, which to a great extent mimics the microenvironment prevailing in the tumour tissue, supporting studies on such tumour specific processes such as angiogenesis, invasion and metastasis and the assessment of responses to various therapies as well as their underlying mechanisms. Developed as an alternative in vitro model to monolayer cultures, nearly 30 years ago, their role as part of high-throughput cell-based assay system in drug discovery is gaining considerable importance. The distinct possibility of establishing MCTS from primary tumour cells and co-culturing with different normal cells, namely stromal fibroblasts, endothelial cells and cells of hemopoietic as well as immune system lineage, enhance the value of MCTS in cancer research and drug development. Here, the authors present a brief overview on the present status on the application of multicellular spheroids in experimental oncology, particularly from the view point of cancer therapy and drug development.