Background Many patients admitted to coronary care unit(CCU) and receive several drugs, these drugs save their life at the other hand these drugs are considered threatened to their life so that nurses should ensure that is safe and effective through careful evaluation of the patient's response to therapy by direct observation of physiological measures Aim of this study: was to evaluate the effect of teaching program about drugs that affect blood coagulation on nurses' performance in CCU. Study design: Quasi experimental (pre-posttest) design was used. Setting: the study was conducted in CCU at Assuit General Hospital. Sample: (30) nurses from the previous mentioned setting. Tools; two tools: were utilized in the present study Tool (1) Knowledge assessment tool by using structure interview questionnaire for nurses was utilized, Tool (2) Assessment tool for nurses' practice by using observational check list for nurses' practice was utilized, Results: nurses' knowledge was improved significant from 25.8±6.48 to 60.63±1.19 and nurses practice was improved from 103.87±9.83 to 169.9±1.86 after implementation of teaching program about drugs that effect blood coagulation in CCU. Recommendation: continues nursing education and training program at CCU should be organized regarding drugs affecting blood coagulation.