Purpose: The study was done to describe competency level in communication and professional competence of Public Health Nurses and to test effect of competency level in communication on professional competence of Public Health Nurses (PHNs). Methods: A correlational research design was used and 153 PHNs working at nine Public Health Centers (PHCs) in four Metropolitan cities agreed to participate. Participants completed a structured questionnaire measuring the study variables with socio-demographic characteristics. Data were analyzed using descriptive statistics and multiple regression analysis with the PAWS Statistics 18. Results: The mean of competency level for communication and professional competence were above average for the test instruments utilized (90.3 and 68.4 respectively). The level of communication competency differed by age and location of PHCs, and professional competence differed by location of the PHCs. The level of communication competency was the most important affecting professional competence and explained 32.9% of the professional competence. Conclusion: Nurses with better communication competency had more professional competence. In the future, repeated study is needed, and communication program is needed to develop and train PHNs to improve their professional competence.