The differential diagnosis of scrotal tumors is not always an easy matter. The peculiar anatomical conformation of the parts, the varied morbid alterations of structures normally located, and the frequent intrusion within the scrotal pouch of dislocated or adventitious tissue renders a positive diagnosis difficult, if not indeed impossible in certain cases. It has been our fortune to witness a number of grave errors of judgment as to the nature of tumors within the scrotum, and our misfortune to occasionally participate in these mistakes. When we consider that a scrotal tumor may be a hernia, hydrocele, orchitis, epididymitis, varicocele, cancer, sarcoma, hæmatocele, or a complication of two or more of these affections, the reason for an occasional blunder is more apparent—and an allusion to previous mistakes may be a reminder of certain diagnostic points that will serve to warn the members of this Society from pitfalls where others have stumbled.