This paper reports an evaluation the utility of ISO/IEC 9126. ISO/IEC 9126 is an international standard intended to ensure the quality of all software-intensive products including safety-critical systems where lives are at risk if software components fail. Our evaluation exercise arose from an experiment that required a quality assessment of outputs of the design process. Although ISO/IEC 9126 is intended to support evaluation of intermediate software products, both the experimental subjects (158 final year computer science and engineering student) and experimenters found the standard was ambiguous in meaning, incomplete with respect to quality characteristics and overlapping with respect to measured properties. We conclude that ISO/IEC 9126 is not suitable for measuring design quality of software products. This casts serious doubts as to the validity of the standard as a whole.