How does a pathologist become interested and develop expertise in testicular and paratesticular neoplasms, which are relatively uncommon? The truth is simple-the opportunity to see many cases. The authors of this 5th Series Fascicle have such expertise and share a remarkable range of cases from their institutions as well as from many pathologists throughout the world who have sent them cases in consultation over the years. This fascicle is rich source of material that will be a great resource for practicing pathologists and pathologists in training.