The concepts of clinical significance and statistical significance each makes a separate and complimentary contribution to the development and approval of pharmaceuticals and devices. Both concepts are debated during study design, study monitoring, regulatory review, manuscript submission, post-approval reviews, and by the end users (physicians and patients). From a regulatory perspective statistical significance is often the easier to define and is often based on strict adherence to the fixed probability that an observed difference between two groups occurred by chance in less than one in twenty cases. Clinical significance may be a much more elusive concept with a strong dependency on the individual(s) or group(s) making the judgement. The presentation will include a discussion and some examples of the sometimes complicated relationship between clinical and statistical significance.