The paper attempts to evaluate some software design metrics, using data from a communications system. The design metrics investigated were based on the information flow metrics proposed by Henry and Kafura, and the problems they encountered are discussed. The slightly simpler metrics used in this study are described. The ability of the design metrics to identify change-prone, error-prone and complex programs was contrasted with that of simple code metrics. Although one of the design metrics (informational fan-out) was able to identify change-prone, fault-prone and complex programs, code metrics (i.e. lines of code and number of branches) were better. In this context ‘better’ means correctly identifying a larger proportion of change-prone, error-prone and/or complex programs, while maintaining a relatively low false identification rate (i.e. incorrectly identifying a program which did not in fact exhibit any undesirable features).