Purpose: This systematic review and meta-analysis aimed to determine whether cricoid pressure protects against aspiration and whether this technique adversely affects intubating conditions in adult patients. Methods: A systematic review of five databases was performed for randomised controlled trials comparing cricoid pressure to no cricoid or sham cricoid during intubation. The primary outcome was incidence of aspiration and the secondary outcomes included first attempt intubation success, time to intubation, Cormack and Lehane Grade 3 or 4 and difficult intubation. Results: The search identified twelve high quality RCTs with 4,862 patients for inclusion. Among four studies reporting the primary outcome, there was no difference (RR=1.18; 95%CI=0.71 to 1.96; I2=0%; p=0.51). Only 3 studies were in patients at high risk of aspiration. There was significantly worse first attempt success (RR= 0.94; 95%CI= 0.89 to 0.99; I2=66%; p=0.02), time to intubation (WMD= 6.77seconds; 95%CI=4.40 to 9.14seconds; I2=97%) and laryngoscopy views (RR=1.69; 95%CI=1.41 to 2.02;I2=1%; p<0.00001) with cricoid pressure. Conclusions: Cricoid pressure failed to show any increase in protection from aspiration and may increase difficulty of intubation. Further studies in high-risk patients, such as intensive care patients, are required.