Hematotoxicology is concerned with the adverse effects of xenobiotics on hematopoietic processes in a living system. In vitro tests for hematotoxicity have been applied in toxicity assessment of chemicals, drugs, food supplements and environment related studies. Hematopoietic Progenitor Colony-Forming Cell (CFC) assays and Stromal Cell Assays (also called as Non-hematopoietic Progenitor Assays) are already being used to detect hematological toxicities induced by different contaminants. These in vitro tests have been very useful in reducing the number of animals required for hematotoxicity testing. In this review, applications, limitations and future prospective of in vitro tests for hematotoxicity with emphasis on the techniques involved in the Colony forming unit culture systems are described.