Cancer, which is one of the most dreaded diseases of the century with the number increasing yearly, is a highly complex process which requires various in vivo models to elucidate the mechanism of action of the newly developed chemotherapeutic agents and or isolation of lead phytomolecules along with other in vitro experiment protocols, before entering into clinical trial phase. This review article deals with some of the in vivo cancer models that may help in this process which include various murine models, spontaneous tumour models, laying hen models, drosophila models, chorioallantoic membrane models, zebra fish models etc.