Introduction In the last few years, pharmaceutical technology has evolved. In the field of oncology pharmacy, robots for the preparation of anti-cancer drugs have appeared to progressively replace manual preparation. The objective of this study is to evaluate the contribution of the robot in reducing the risk of manual preparation. Methods The study was conducted at the pharmacy of the National Institute of Oncology in Rabat (May–August 2021). The method used to compare the two types of preparation is the method of analysis of failure modes, their effects and their criticality (FMECA). It will calculate the criticality index (CI = severity × frequency × detectability). The risks have been categorized into human, technical, and environmental risks. Results The anticancer drugs reconstitution step was the most critical in manual preparation (CI = 126.7) and robotic preparation (CI = 40.7). The robot has made it possible to reduce several CIs of manual preparation including: musculoskeletal disorders of pharmacy operators −93 (89%), error in cancer drug and diluent selection −72 (60%), as well as lack of traceability −145 (97%). Conclusion The preparation robot has made it possible to reduce many of the risks of manual preparation, and constitutes an important advance in the field of oncology pharmacy.