Background: Needlestick injuries (NSIs) are percutaneous injuries sustained with sharp equipment used in the delivery of medical care. They are common occupational hazards occurring among health care workers and are a potential source of transmission of bloodborne pathogens. descriptive cross-sectional study was conducted to determine the prevalence and identify predisposing factors to needle stick injuries and to assess rates of utilization of post-exposure prophylaxis among resident doctors in a tertiary hospital in Nigeria. Methods: A descriptive cross-sectional study design was used. A multistage sampling method was used to recruit 210 resident doctors of the University of Port Harcourt teaching hospital into the study. Data was collected using a structured self-administered questionnaire to ascertain the history of a needle stick injury, the number of injuries in the past one year, perceived cause of the injury, reporting of the injury, the use and completion of post-exposure prophylaxis. Findings: Overall response rate was 94.5%. The study found a 53.8% lifetime prevalence of NSIs among resident doctors. Annual prevalence was 50.9%. The prevalence was significantly higher among senior registrars(65.1%) than junior registrars (p=0.006), among residents in Paediatrics (75.6%), Obstetrics and Gynaecology (72.7%) and Surgery(63.9%) than among those in other departments (p<0.001), and among residents who had spent three years or more (65.7%) than those who had spent less than three years (p<0.001). The most frequently reported factors that predisposed residents to needle stick injuries were excessive workload (77.9%), insufficiency of consumables (72.6%), long working hours (70.2%) and lack of personal protective equipment (69.7%). All the residents were aware of the risk of transmission of infection through NSIs. About 77.4% of residents had negative attitudes of recapping needles, 66.1% had negative attitudes of not reporting NSIs to appropriate authorities, whereas 73.2% had positive attitudes of taking protective actions in response to NSIs. Only 8.9% of the residents utilized post-exposure prophylactic services after sustaining NSIs. In 51.8% of cases, the needle had been used on the patient prior to the injury. In 25.9% of these cases, the injury involved a high-risk patient (HIV, Hepatitis B or C infected). study found the risk of transmission of HIV following a needle stick injury to be 0.48%. Interpretation: Needlestick injuries are common among resident doctors however, a large number of these injuries go unreported, the level of awareness about NSIs and the risk of transmission of infection is high, however, the attitude toward preventive measures and use of post-exposure prophylactic services was poor. Even though the risk of disease transmission is relatively low, there is an urgent need for the improvement of doctors' safety culture towards infection prevention which requires in-service training, addressing problems of man-power and shortage of consumables. Funding Statement: The authors reported: This study was author funded. Declaration of Interests: The authors stated: No potential conflict of interest relevant to this article is reported. Ethics Approval Statement: Informed consent was obtained. Confidentiality was maintained. Participation was voluntary, Ethical approval was obtained from the University of Port Harcourt Ethics committee.