Background: Venous thromboembolism is the most common cause of preventable death in hospitalized patients worldwide. More than 80% of thromboembolic illnesses in pregnant women are venous thromboembolism (VTE), and the prevalence of VTE is significantly higher in pregnant women than in non-pregnant women. The disease is highly insidious, develops rapidly and seriously endangers the health and life of the pregnant women. It is important that maternity and critical care nurses to have sufficient knowledge and skills about preventive measures of VTE. Aim: evaluate the effect of training program on maternity and high-risk nurses' performance (knowledge and practice) regarding preventive measures of VTE. Design: A quasi-experimental design was used. Setting: The study was conducted in high-risk pregnancy units and intensive care unit at Beni-Suef University Hospital. Sample: All convenient samples 50 nurses. Tools: Two tools were used (1) a self-administered questionnaire sheet to assess knowledge, (2) an observational checklist to assess practice regarding preventive measures of VTE. Results: preprogram; the majority of the nurses had unsatisfactory knowledge and practice regarding preventive measures of VTE (82% and 92% respectively). A significant improvement was found immediately post-program (86% and 88%, respectively) while this improvement lowered slightly post 3 months at follow up (72%and 70% respectively). Conclusion: A statistically significant improvement in nurses' performance had got after implementation of the program which supported the study hypothesis. Recommendation: Continuous in-service training programs about preventive measures of VTE.