As object oriented analysis and design techniques become widely used, the demand on assessing the quality of object-oriented designs substantially increases. Recently, there has been much research effort to develop and empirically validate metrics for OO design quality. Complexity, coupling, and cohesion have received a considerable interest in the field. Despite the rich body of research and practice in developing design quality metrics, there has been less emphasis on dynamic metrics for object-oriented designs. The complex dynamic behavior of many real-time applications motivates a shift in interest from traditional static metrics to dynamic metrics.This paper addresses the problem of measuring the quality of object-oriented designs using dynamic metrics. We present a metrics suite to measure the quality of designs at an early development phase. The suite consists of metrics for dynamic complexity and object coupling based on execution scenarios. The proposed measures are obtained from executable design models. We apply the dynamic metrics to assess the quality of a pacemaker application. Results from the case study are used to compare static metrics to the proposed dynamic metrics and hence identify the need for empirical studies to explore the dependency of design quality on each.