Breastmilk is the best nutrition for infant but giving only breastmilk for preamature infants older than 2 weeks could not comply the needs and has to be fortified Human milk fortifier HMF is very recommended to fortify breastmilk In west Sumatera including DR M Djamil Hospital HMF was unreachable and expensive At certain hospital in Africa and several Hospital in United States they exclusively use fortified breastmilk with Post Discharge Formula PDF Objective To compare the weight gain among premature infants receiving fortified breastmilk with PDF and premature formula milk and also to observe the adverse event Methods A 4 weeks experimental study on premature infants gestational age ge 28 until 37 weeks who receive fortified breastmilk with PDF and some of them received premature formula milk acted as a control from March until December 2015 in DR M Djamil Hospital West Sumatera Results Data was obtained from 30 sample for each group intervention and control Sample baseline characteristic such as sex gestational age GA birth weight and previous illness history was indifferent statistically The mean of birth weight in control group was 1643 grams the mean of weight at the initial study was 1631 grams and the mean of birth weight at the end of study 4 weeks was 2573 grams The mean of birth weight in intervention group was 1682 grams the mean of weight at the initial study was 1722 grams and the mean of birth weight at the end of study 4 weeks was 2775 grams The mean of time to reach full feed condition initial study in control group was 14 days and 18 days in intervention group The mean of weight gain during 4 weeks was 958 grams in control group and 1053 grams in intervention group p 0 22 There was no adverse event found in infants received both breastmilk fortified with PDF and premature formula milk Conclusion It appears that weight gain of premature infants who receive breastmilk fortified with PDF is indifferent statistically compared with premature infants who receive formula milk There is no adverse event found in this study