Biological hazards are one of the most common health risks and the most harmful exposure to health care professionals. Health care professionals are constantly exposed to microorganisms that can cause serious or even lethal infections. Nurses in particular are often exposed to various infections during the course of carrying out their activities. Therefore, nurses should have sound knowledge and strict adherence to infection control practice. Aim: This study aimed to assess nurses' knowledge, practice and attitude regarding preventive measure of biological hazards. Design: Case study design was used and conducted on 141 of nurses working at Mansoura Health Insurance Hospital. Four - structured questionnaire were used throughout the study for exploring nurses demographic data and occupational characteristics, their knowledge , practice and attitude related to biological hazards. Results: The majority of nurses (85.8%) had positive attitude regarding to preventive measures of infection, while 14.2% of nurses had negative attitude. The study showed insignificant negative correlation with educations, and years of experience, there was a significant positive correlation between total knowledge score and total attitude score. The study showed that all of the nurses had unsatisfactory practice related to infection control measures. Conclusion: It is necessary to assess nurses' knowledge, practice, and attitude regarding preventive measure of biological hazards to reduce varied unacceptable nurse's practice and raise quality of care. There is a need for educational program about universal precautions especially about handling of the sharps.