Background: Medical ethics require the physician to do what is best for the patient and place the patient's interests before the interests of the physician. It is not about avoiding harm; rather, it is a set of norms, values and principles. Objectives: To assess medical ethics knowledge and practice and its associated factors among healthcare workers at PMMH, Taif, Saudi Arabia, 2012. Methodology: This was a cross sectional study including all healthcare workers at PMMH who were present at the time of study conduction. Self-administered questionnaire which had been validated in previous published studies was utilized for data collection. The questionnaire is composed of 16 points which cover the 6 of the values that commonly apply to medical ethics as followings: autonomy, beneficence, non-maleficence, justice, dignity and truthfulness and honesty. Participates were assessed for knowledge regarding each single aspect of ethical issues with a grade scale (likert scale) from 1 to 3 (ranging from disagree to agree). Results: Overall, 224 of 270 health care workers, invited to participate in the study by filling out the research questionnaire, returned completed questionnaires, giving a response rate of 83.0%. Their age ranged between 24 and 52 years with a mean of 31.7(SD 6.0) years. Three-quarters of them (168; 75.0%) were females. 42.4% of healthcare workers had bad knowledge regarding medical ethics, mostly doctors (56.8% versus 35.3% of nurses). Very good or excellent level of medical ethics knowledge was reported among 21.4% and 7.1% of healthcare workers, respectively. Nurses reported more significant very good and excellent knowledge than doctors (30% versus 25.7%). Conclusion: More than 40% of healthcare workers in PMMH had bad knowledge regarding medical ethics, mostly doctors. Nurses reported more significant medical ethics knowledge than doctors. There were varying opinions in many issues of care-ethics.