Two longitudinal studies of infant growth, performed from 1985 to 1988 in the Copenhagen area, have been combined to develop an up-to-date growth reference. Percentile curves were constructed and median growth velocities were calculated for monthly intervals, based on individually estimated growth curves. Compared with references based on data from periods when the prevalence of breast-feeding was low, these data support previous suggestions of a new growth pattern, with higher velocities during the first months and slower velocities during the remaining infancy. The growth of breast-fed infants differs from that of infants not being breast-fed, and special growth references for breast-fed infants have been suggested. We therefore examined growth patterns in the present study according to duration of breast-feeding. At 12 months, infants breast-fed > or = 9 months weighed less (400 g (95% CI: 70 g, 740 g) and were 1.0 cm shorter (0.3 cm, 1.8 cm) than infants breast-fed < 9 months. Part of this difference was already present at six months. Despite this we recommend a single growth reference for Danish infants regardless of mode of feeding. The slower growth in infants breast-fed > or = 9 months, which could be due to differences in composition of weaning foods, should be investigated further.