Background: Prostatic leiomyoma is a benign and rare condition of the prostate. Robotic surgery is increasingly being applied in the surgical management of prostate cancer. Case Presentation: Herein, a mass lesion that was located in the posterior part of the prostate between seminal vesicles that was identified during robotic surgery is presented. This lesion further challenged the console surgeon during performing a robotic radical prostatectomy procedure for a 200 g large prostate with prostate cancer. Conclusion: Prostatic leiomyomas that are benign mesenchymal smooth muscle tumors might present as a posteriorly located mass lesion between seminal vesicles that could challenge the surgeon during surgery, which should be kept in mind.