Tumor metastasis represents a major problem in the treatment of patients with different cancers. Specific phenotype and behavior of metastatic cells derive from specific molecular mechanisms involved in consecutive steps of the metastatic process. Several in vitro and in vivo experimental models have been utilized, but they cannot completely reproduce and characterize each step of the metastatic process. This review article is focused on the chick embryo chorioallantoic membrane as an in vivo model to study the metastatic process.