Episode 4 of CRAMSURG - Clinical Reasearch Appraisal and Methodology for Surgical Trainees. The paper for discussion is Perianal block with ropivacaine as a supplement to anaesthesia in proctological surgery: double‐blind randomized placebo‐controlled trial (PERCEPT), BJS March 2020. The teaching topic is Randomised Clinical Trials: Randomisation and Bliding. Brought to you by CRAMSURG www.cramsurg.org.