Background: Blood transfusion has a positive effect on patient life, so nurses' plays an integral role to maintain patient safety related to blood transfusion. Aim of the study: The present study was aimed to assess knowledge of nurses regarding blood transfusion at public hospitals in Sana'a City-Yemen Method: A descriptive cross-sectional design study was utilized in this study; 93 nurses were employed in public hospitals in Sana'a–Yemen. Selfadministered questionnaire was used to collect data from October 2020 to November 2020. Results: The most of study participants were employed labor room department 44.1%, belonged to age group (26 to 30 years) 33.3%. The Diploma degree was the most available qualification 69.9%, 83.7% had 6 to 10 years' experience as nurses, while 85.60% of them h <1-5 years' experience in an ICU. The most 71%of nurses were not trained. Knowledge regarding blood transfusion was fair 59.1%, while 25.8% had good knowledge. Conclusion: The most of nurses had fair knowledge regarding blood transfusion. Recommendation: Transfusion training and evidence-based guidelines are needed to reduce inappropriate transfusions and improve patient care.