A number of the more commonly used graphical representations of flow cytometric data are described and assessed in terms of the nature of the information they are best fitted to convey. These include single parameter distributions, two-parameter contours, three-dimensional two-parameter distributions, three-dimensional three-parameter contours and "raw data" two-parameter dot plots. The effect of the degree of sophistication of the instrument from which such data is obtained is taken into account in indicating techniques for obtaining and recording the maximum amount of information for each sample.