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Birthweight and neo-natal mortality date for White and Nonwhite single birth infants born in Virginia (USA) for each year from 1955 through 1973 are presented and analyzed. Data are grouped into nine birthweight categories. Over time, the number of infants born in any of the nine categories does not change significantly, though the number in each category for White infants is significantly higher than for Nonwhite infants. In the four lower birth weight categories, Nonwhite infants show significantly lower neo-natal mortality rates than White infants while the reverse is true in the four highest birthweight categories. Mortality rates in the three lowest birthweight categories change with time: mortality rates peak in the late 19.50s, steadily decline during the 1960s and appear to level off or slightly increase in the 1970s. The optimal birthweights and the lower and upper discriminating birthweights do not change significantly over time, although there appears to be a slight downward trend in the lower discriminating birthweight. Possible factors responsible for the observed differences and changes are discussed. These include differences in the gestational ages of White and Nonwhite infants of similar birthweight, inap­propriate use of certain antibiotics, and improved intensive-care techniques.