OBJECTIVE This article investigates the effects of a brief psychological intervention-implementation intentions training-on the reduction of saturated fat intake among patients after myocardial infarction (MI). METHODS One hundred fourteen patients who had experienced a first uncomplicated MI took part in the study. Data were collected at approximately 1 week after MI, 2 weeks after short-term Phase 2 cardiac rehabilitation (approximately 2 months after MI), and 6 months after rehabilitation (8 months after MI). After data collection at 2 weeks after rehabilitation, patients were randomly assigned to the control group or the intervention group (an individually delivered implementation intentions training). Daily saturated fat intake was used as the primary outcome; total fat intake and percentage of calories from fat were secondary outcomes. RESULTS Repeated-measures analysis of variance showed a significant TimexGroup interaction: Compared to time before MI, patients in both groups reported a decrease in saturated fat intake at 2 weeks after rehabilitation. Those who participated in the implementation intentions intervention were able to further decrease saturated fat intake from 22.88 g at 2 months after MI to 19.71 g at 8 months after MI. Patients from the control group maintained the same level of saturated fat intake at 2 months after MI (mean=22.30) and 6 months later (mean=22.47). CONCLUSIONS An individually delivered implementation intentions intervention may reduce saturated fat intake among patients after MI.