The availability of metrics for measuring software design quality and complexity are a great help in the development of such systems. Applications of such metrics in the initial stage of the software development process (specification, analysis, and design) allows us to detect those software designs which are excessively complex or intricate at a time when correction costs are still low. In this way, we are able to avoid all the negative consequences that badly-designed systems may involve, such as high maintenance cost, poor re-use, proneness to error, low portability to different environments, ... Whereas there is a large number of studies and reviews on the measurement of systems which have been developed by means of procedural methods, this is not the case for systems designed through the object-oriented paradigm. In this paper we present a collection of measures which can be useful for measuring object-oriented systems and which may also help to extend the research so far carried out in this field.