Abstract Objective. This study describes the study design and procedures for a prospective, non-randomized trial comparing open retropubic and robot-assisted laparoscopic radical prostatectomy regarding functional and oncological outcomes. Material and methods. The aim was to achieve a detailed prospective registration of symptoms experienced by patients using validated questionnaires in addition to documentation of surgical details, clinical examinations, medical facts and resource use. Four patient questionnaires and six case-report forms were especially designed to collect data before, during and after surgery with a follow-up time of 2 years. The primary endpoint is urinary leakage 1 year after surgery. Secondary endpoints include erectile dysfunction, oncological outcome, quality of life and cost-effectiveness at 3, 12 and 24 months after surgery. Results. The study started in September 2008 with accrual continuing to October 2011. Twelve urological departments in Sweden well established in performing radical prostatectomy are participating. Personal contact with the participating departments and patients was established to ascertain a high response rate. To reach 80% statistical power to detect a difference of 5 absolute per cent in incidence of urinary leakage, 700 men in the retropubic group and 1400 in the robotic group are needed. Conclusions. The Swedish healthcare context is well suited to performing multicentre long-term prospective clinical trials. The similar care protocols and congruent specialist training are particularly favourable. The LAPPRO trial aims to compare the two surgical techniques in aspects of short- and long-term functional and oncological outcome, cost effectiveness and quality of life, supplying new knowledge to support future decisions in treatment strategies for prostate cancer.