Small, incidental testicular lesions are often benign, but in the past have usually been treated by orchidectomy. An alternative is an operative excision biopsy, with localization by ultrasound if necessary, and characterization of the lesion by frozen section analysis. The present review summarizes the indications for the procedure, lists the likely diagnoses, and describes the technique. Frozen section is accurate for distinguishing benign from malignant lesions, testicular function is usually preserved, and there is no evidence that oncological safety is impaired. Such testis-preserving surgery is a rewarding ground for collaboration between urologists, radiologists, and pathologists.