Motivational interviewing is a patient-centered directive approach to enhance intrinsic motivation to behavioral change by helping patients explore and resolve ambivalence between the desired behavior and their actual behavior. This study aimed to assess the effects of a motivational interviewing as Psychiatric nursing program on smoking cessation among smoker patients with heart disease to increase motivation and promote change. Research hypothesis: The motivational interviewing as a psychiatric nursing program will have a positive effect on smoking cessation among smokers' patients with heart disease. Design: quasi-experimental design (one group pre-test post-test design) was utilized to achieve the aim of the study. Setting:-The study was conducted at outpatients' clinic in Benha University Hospital. Subjects: - Purposive sampling of the present study were 40 patients with heart disease. Tool of Data Collection: The tool was divided into four parts: 1st part: Socio-demographic data 2nd part: Fagerstrom Test for Nicotine Dependence (FTND) questionnaire (1991) .3rd part: Readiness to Change Questionnaire was adopted from Rollnick et al., (1992). 4th part: Assess the need to quit smoking SCAN adopted from Zeldman et al.,(2004) .The main findings of the study were: There are highly statistically significant differences regarding to Nicotine dependency level, Readiness to change and Need to quit smoking between pre and post program interventions. Conclusion: Based on the findings of the present study, it is concluded that motivational interviewing intervention had appositive effect on smoking cessation among smoker patients with heart disease. Recommendation: Professionals at every level of the healthcare system should have the ability to quickly assess patients’ smoking status, provide factual information on the harms of tobacco use, and help inspire patients to quit by employing a strategy called Motivational Interviewing