- Introduction and objectives: Cryosurgical ablation of the prostate is a promising new modality for the treatment localized prostate cancer. However, better protection of the rectal wall during cryoablation of the peripheral zone of the prostate (PZP) may permit deeper freezing of the PZP and for longer time, rendering the procedure safer and more effective. We present a modified cryoablation technique of the prostate using the SeedNet™ system (Galil Medical, Uniondale, NY, USA), in which the rectum is actively protected during cryoablation. Patients and Methods: During a 12-month period, 31 patients (32 procedures) with localized and histologically proven prostate adenocarcinoma of various stages and grades were treated in this fashion. We evaluated the feasibility of a new method of active rectal wall protection during cryoablation of the prostate. Fourteen ultrathin, 17-gauge, probes, cryo-needles were percutaneously introduced under transrectal ultrasound (TRUS) guidance into the prostate. Peripheral region of the prostate and the area between the prostate and rectal wall were real time monitored for temperature changes. Two cryo-needles placed between the prostate and rectal wall served for active warming using the thawing mode when the temperatures dropped to approximately 0 °C, and rectal lumen washing with hot water (+40 °C) when the temperature reading dropped further to −8 °C or −10 °C. Results: Active protection of the rectal wall using the cryosurgical modification of active thawing by the two additional cryo-needles placed in the space between the prostate and rectum, while freezing the prostate was performed in every patient, thus enabling us a safe generation of an iceball at the peripheral zone of the prostate with an average temperature ranging from −35 °C to −60 °C, for 10 min per cycle. During a follow-up of up to 18 months (mean 13.2 months) there was a PSA decrease to values equal or less than 0.5 ng/ml in 25 patients (80.6%) and to values equal or less than 1 ng/ml in 21 patients (67.7%). There were no cases of rectal injury or postoperative rectal pain in any of these patients. Conclusions: This new cryotechnique of active rectal wall protection during cryotherapy of the prostate was safe and simple to perform, resulting in no rectal injuries. It was also very effective in ablating the prostate gland, as expressed by the low follow up PSA values.