Both cholecystographic and sonographic analysis of the contraction of the gallbladder showed good correlation between relative decrease of gallbladder width and relative decrease of the area or volume (R = 0.86, p less than 0.001, n = 14, R = 0.80, p less than 0.05, n = 7 respectively). Therefore, we used the relative decrease in the width of the gallbladder to predict the relative decrease in volume. The volume was calculated using a formula given in the literature, after determination of the length, width and depth, using realtime sonography. Correlation between the calculated relative decrease of volume of the gallbladder and the predicted value, was good (R = 0.90, p less than 0.01, n = 8). The relative decrease in the width of the gallbladder in the with of the gallbladder! Can therefore represent the Contraction of the whole gallbladder. Due to its simple method of determination it can be recommended as a complement to sonography of the gallbladder. First of all, however, it will be necessary to conduct a study in a relatively large number of healthy volunteers to obtain the reference values.