Purpose: The purpose of this study was to measure the effects of a breastfeeding management program for promotion of breastfeeding. Method: The study design was a non-equivalent control group pre-post test. The study subjects were pregnant women receiving a breastfeeding education class in one hospital in Ilsan. The total number of study subjects was 153 pregnant women, namely 75 mothers in the experimental group and 78 in the control group. Data was collected between June and November, 2006. A breastfeeding management program was provided to the experimental group while admitted for delivery, and in weeks 2, 4, 8, 12, 16, 20, and 24 of the postpartum period. The rates of breastfeeding were measured in weeks 2, 4, 8, 12, 16, 20, and 24 of the postpartum period. Result: There were significant differences in the scores of rate of breastfeeding between the two groups(all cases), which were 93.1 in the experimental group and 85.8 in the control group at week 4; 88.1 vs 71.8 at week 8; 83.4 vs 56.7 at week 12; 71.4 vs 53.9 at week 16; and 65.7 vs 48.4 at week 20 respectively. However, there were not significant differences in the scores of rate of breast-feeding between the two groups, which were 97.7 in the experimental group and 96.0 in the control group in the early postpartum period at week 2, and 59.6 vs 45.3 at week 24. Add to this, the study analyzed only people who had jobs. As a result, the scores of rate of breastfeeding were 94.8 in the experimental group which were significantly higher than 88.5 in the control group at week 4; 93.2 vs 73.3 at week 8; 89.6 vs 57.2 at week 12; and 75.0 vs 46.0 at week 20 respectively. However, there were not significant differences at week 2, week 16 and week 24. Conclusion: The results of this study suggest that a breastfeeding management program during the last trimester of the perinatal period and postpartum period may increase the duration of breastfeeding in postpartum clients who intend to breastfeed. This study supports the literature which found that prenatal education and postpartum support are important to the outcome of breastfeeding.