The study purpose was to evaluate the relationships between average volume of a swallow (AVS) and age, height, weight, sex, and container-opening diameter (COD) to confirm and expand the work of Jones and Work. Forty-five males and 50 females between two and 18 years of age were studied. Each subject drank five swallows from each of four containers. AVS for each subject under each condition was calculated and the joint relationship with the independent variables analyzed by multiple regression. Age, height, and weight were highly intercorrelated, and each had similar correlations with AVS. COD was important; between 24 and 90 months of age, swallows from the 6.5 cm COD had a three- or four-fold larger AVS than swallows from the 1.5 cm COD. Sex differences in AVS were noted in subjects over seven years of age. These findings suggest that determination of the child's age and number of swallows ingested may be useful in estimating the fluid volume ingested and the potential toxicity of an exposure.