Human milk is the first choice for infant nutrition but it must be multinutrient fortified for optimum growth and neurodevelopment in preterm infants. However, there is no consensus on ideal fortification method. The authors aimed to generate the human-milk protein content percentiles during the first five postnatal weeks in four preterm groups (n = 108) with median gestational age of 32 (23-36) wk, who were fed adjustably fortified breast milk in the NICU between October 2011 and June 2013. Total 540 breast milk samples of mothers of 108 infants were weekly analyzed for protein intake. It was observed that the median human-milk protein levels decreased throughout the five postnatal weeks in all groups. None of the preterm infants was able to take the recommended daily protein intake with the fortification protocol of the authors' unit. Preterm human-milk protein charts can be used as a new practical individualized fortification guiding method instead of laborious targeted or adjustable approaches currently in use.