SUMMARYThe use of the ‘point‐sampled intercepts’ method on histopathological material is evaluated for the main purpose of comparing different methods of intercept length measurements. The volume‐weighted mean nuclear volume—nuclear—of the carcinoma of the ampulla of Vater is calculated using three methods for measuring intercept lengths: a semiautomatic image analyser, an equidistantIo‐ruler and a logarithmic‐ruler. Rulers of several classes and lengths are used, and the results of the nuclearestimations are compared. The equidistantIo‐ruler is more accurate than the logarithmic‐ruler. With a greater number of ruler classes and with adjustment of ruler length to the greatest nuclear intercept lengths, the systematic deviation from the true value of the nuclearis smaller. The nuclearparameter has great power to differentiate intestinal carcinoma