This paper deals with the application ofz-transform techniques to the analysis of sampled-data systems in which signals appear in pulse duration modulated form. The characteristics of pulse duration sampled data are first briefly described. An analytical means for studying the transient response and stability of systems which use this kind of data is then presented. Finally, a comparison is shown of analytical results with tests on several representative experimental systems. A short discussion of the relative advantages and disadvantages of pulse duration modulation in control systems is also included.