Purpose: This study was done to identify effects of a smoking cessation program including telephone counseling and text messaging using stages of change for outpatients who have had a myocardial infarction (MI). Methods: This research was a quasi-experimental design with a nonequivalent control group pretest-posttest. The participants were 48 outpatients (experimental group=24, control group=24) recruited from one university hospital. They were randomly assigned to one of two groups: (a) an experimental group with telephone counseling (once a week) and text messaging (five times a week) using stages of change, and (b) a control group with traditional telephone counseling (once a month). Efficacy of the intervention was measured by comparing the two groups on smoking-related variables at 3 weeks and 12 weeks. Results: At the 3-week and 12-week measurements, there were significant differences between the experimental and control groups on smoking cessation self-efficacy (p<.001), nicotine dependence (p<.001), CO levels (p<.001), and smoking cessation rates (p<.001). Conclusion: The results indicate that the smoking cessation program including telephone counseling and text messaging using stages of change is effective for outpatients after a MI. Further attention should be paid to the intensity of the smoking cessation program and periods for long-term follow-up.