The aim of this study was to assess birth weight of healthy newborns from the City of Zagreb and Zagreb County, Croatia. Birth weights of healthy newborns, born at the Department of Obstetrics and Gynecology, University Hospital Center "Zagreb" in the year 2001, were included into analysis. Since there were only few newborns in the 22nd-27th week of gestation, they were excluded from the study. Small number of data points was also noticed in 28th-36th week of gestation, and was supplemented with the data from the years 2000, 2002 and 2003. The method of analysis used in this study was described by Altman and Chitty (Br. J. Obstet. Gynaecol., 101 (1994) 29). After the application of well defined exclusion criteria, the final sample consisted of 4252 newborns. Percentile values for the four groups of newborns (male gender-primipara, male gender-multipara, female gender-primipara, female gender-multipara) were defined, yielding highest birth weight values in the male gender-multipara group (50th percentile of 40th gestational week was 3551.3 g), while female gender-primipara newborns were the lightest among the four sub-samples studied (50th percentile of 40th gestational week was 3399.9 g). New percentile values for percentile curves plotting are presented here and recommended for use in the clinical practice.