In armed conflicts, bias significantly influences mediation procedures, yet its specific role still needs to be explored. This chapter examines bias in mediation within the Ukraine conflict, focusing on the Organization for Security and Co-operation in Europe's (OSCE) Special Monitoring Mission (SMM). Content analysis of OSCE member states' interpretations reveals biases favoring Ukraine and disfavoring Russia. Such predispositions, evident in member states' declarations, have implications for international mediation scholars and practitioners. The study underscores the challenges of maintaining impartiality in mediation amidst armed conflicts, emphasizing the urgent need for nuanced understanding to foster more effective mediation processes.