Ultrasound is a routine investigation for the assessment of scrotal masses. Many of the detected lesions involve the paratesticular structures. The most common paratesticular masses in clinical practice are epididymal cysts and spermatoceles, but there are a large number of other pathologies that can be encountered and may result in diagnostic uncertainty. This review covers a wide range of the common and the rare, but important, causes of paratesticular masses. The ultrasound findings (both typical and atypical) of these lesions are clarified, and emphasis is given to the features that help to differentiate between them.