Evidence supports the contribution of depression, anxiety, and poor social support to mortality of hospitalized myocardial infarction (MI) patients. The contribution of depression to survival is independent of disease severity. Pet ownership, a non-human form of social support, has also been associated with one year survival of post-MI patients. The current study addresses whether pet ownership contributes independently to long term survival beyond the contributions of depression, anxiety, or low social support in post-MI patients who have already survived at least 6 months. Data from patients (N = 460) enrolled in the "Psychosocial Responses in the Home Automated External Defibrillator Trial (PR-HAT)"were used. Seventeen patients died during a median follow-up of 2.8 years. In Cox proportional hazards regression model that included depression, lack of pet ownership, and the interaction between depression and lack of pet ownership, not owning a pet was the only significant independent predictor of mortality (p = 0.036). The interaction between pet ownership and depression tended to be significant indicating that the effect of pet ownership on survival in this group of people who have supportive spouses/companions living with them may relate to depression.