Objectives: Few studies have described the survival of low-birth-weight infants weighing less than 1.5 kg at operation for a cardiac malformation. Our goal was to determine if body weight at surgery affects survival. Methods: This was a retrospective cohort study using outcome data from the Pediatric Cardiac Care Consortium between 1982 and 2006. Results: We reviewed the outcomes of 450 consecutive infants with a cardiac anomaly and a birth weight of less than 1.5 kg, and weight of less than 2.5 kg at surgery. Of these, 179 patients had undergone surgery with a weight of less than 1.5 kg and 271 patients weighed 1.5 to 2.5 kg at surgery. The 30-day survival rate was 83% for cohort 1 and 86% for cohort 2. For patients not requiring cardiopulmonary bypass, the 30-day survival rate was 86% for cohort 1 and 92% for cohort 2. For patients requiring cardiopulmonary bypass, the 30-day survival rate was 69% for cohort 1 and 73% for cohort 2. No notable improvement in the outcomes occurred over time. Conclusions: For low-birth-weight infants (weight < 1.5 kg) undergoing a major cardiac procedure, the survival of infants weighing less than 1.5 kg at surgery is comparable to that of infants who weighed 1.5 to 2.5 kg. We conclude that, in our series, weight was not an independent risk factor for mortality, and, therefore, operative delay because of patient weight might be unwarranted.