Laparoscopic Heller's cardiomyotomy (LHC) is the preferred treatment of achalasia. It improves dysphagia by dividing muscles of the lower oesophageal sphincter, but this intervention can result in debilitating gastro-oesophageal reflux symptoms in some patients. To prevent these reflux symptoms, most surgeons add a fundoplication to Heller's cardiomyotomy, but there is no consensus regarding this or the type of fundoplication which is best suited for the purpose. To assess how the addition of a fundoplication affects postoperative reflux and dysphagia in people undergoing LHC and compare the different types of fundoplications used in combination with LHC to determine which is better at controlling reflux without worsening the dysphagia. We searched three databases (CENTRAL, MEDLINE and Embase) on 31 October 2021 and trial registers to identify all published and unpublished randomised controlled trials (RCTs) in any language, comparing different fundoplications used in combination with LHC to treat achalasia. We also included RCTs where LHC with a fundoplication is compared with LHC without any fundoplication. We only included RCTs which recruited adult participants with achalasia undergoing LHC with minimal hiatal dissection. We excluded non-randomised studies or studies involving paediatric participants. We also excluded studies where the procedure was done by open surgery and where circumferential hiatal dissection of the oesophagus was carried out, unless it was necessary to reduce a hiatus hernia or to facilitate a Toupet or Nissen fundoplication. Two review authors independently identified studies to be included, assessed risk of bias using the Cochrane RoB 1 tool, and extracted the data. We calculated the risk ratio (RR) with 95% confidence interval (CI) using both fixed-effect and random-effect models with Review Manager (RevMan) software. We included eight studies in this review, with a total of 571 participants with an average age of 45 years (range 33.5 to 50). LHC without any fundoplication was performed in 65 (11.3%) participants, 298 (52.1%) had Dor fundoplication, 81 (14.1%) had Toupet fundoplication, 72 (12.6%) had Nissen's fundoplication, and 55 (9.6%) participants had angle of His accentuation. Three studies with a total of 143 participants compared LHC + Dor to LHC without fundoplication. We found that the evidence is very uncertain as to whether the addition of a Dor fundoplication made any difference to the outcome of postoperative pathological acid reflux (RR 0.37, 95% CI 0.07 to 1.89; I2 = 56%; 2 studies, 97 participants; very low-certainty evidence) and uncertain for severe postoperative dysphagia (RR 3.00, 95% CI 0.34 to 26.33; I2 = 0%; 3 studies, 142 participants; low-certainty evidence). Three studies with 174 participants compared LHC + Dor to LHC + Toupet. The evidence suggests that there may be little to no difference in the outcomes of postoperative pathological acid reflux (RR 0.75, 95% CI 0.23 to 2.43; I2 = 60%; 3 studies, 105 participants; low-certainty evidence) and severe postoperative dysphagia (RR 0.78, 95% CI 0.19 to 3.15; I2 = 0%; 3 studies, 123 participants; low-certainty evidence) between the two interventions, but the certainty of the evidence is low. One study with 138 participants compared LHC + Dor to LHC + Nissen. Nissen fundoplication caused increased severe postoperative dysphagia (RR 0.19, 95% CI 0.04 to 0.83; 1 study, 138 participants; high-certainty evidence) when compared to Dor fundoplication. This study did not show a difference in postoperative pathological acid reflux (RR 4.72, 95% CI 0.23 to 96.59; 1 study, 138 participants; low-certainty evidence), but the certainty of evidence is low. One study with 110 participants compared LHC + Dor with LCH + angle of His accentuation, and reported that severe postoperative dysphagia was similar between the two interventions (RR 1.56, 95% CI 0.27 to 8.95; 1 study, 110 participants; moderate-certainty evidence), with moderate certainty of evidence. This study did not report on postoperative pathological acid reflux. When LHC was performed with minimal hiatal dissection, we were very uncertain whether the addition of a Dor fundoplication made a difference in controlling postoperative reflux, and we were uncertain if it increased the risk of severe postoperative dysphagia. There may be little to no difference in the outcomes of postoperative pathological acid reflux or severe dysphagia between Dor and Toupet fundoplications when used in combination with LHC, but the certainty of the evidence is low. Nissen (total) fundoplication used in combination with LHC for achalasia increased the risk of severe postoperative dysphagia. The angle of His accentuation and Dor fundoplication had a similar effect on severe postoperative dysphagia when combined with LHC, but their effect on postoperative pathological acid reflux was not reported.