Ano-genital distance (AGD) obtained from male and female mice at birth correlated significantly with body weight. Body length did not correlate significantly with AGD in females. Although it did so in the males, the coefficient accounted for less than half of the variance relative to that obtained by correlating AGD with weight. It is suggested that transformed AGD scores (AGD/body weight) rather than raw AGD data be analyzed when AGD is used to determine whether an independent variable that may affect body weight influences the prenatal hormone milieu.