Prostate cryoablation was introduced in clinical practice in 1995. Thanks to the intraoperative ultrasound imaging control, it was among the first echo-guided treatment approaches in urology. The role of ultrasound is essential both for verifying the positioning of cryoprobes and for monitoring the freezing phases. Liquid nitrogen, used by the first-generation machines, was then replaced by argon (an inert gas), which is based on the Joule–Thomson effect in modern cryoprobes. The argon in the transition—from liquid to gaseous state—allows it to reach temperatures of −180 °C in a very short time. Nowadays, focal or whole-gland cryoablation is a possible treatment option within a clinical trial setting as the primary treatment of localized prostate cancer and as a salvage treatment in localized prostate cancer that relapsed after radiotherapy.