Background: Laparoscopic adrenalectomy (LA) has replaced open adrenalectomy as the standard operation for non-malignant adrenal tumours. Retroperitoneoscopic adrenalectomy (RA) is an increasingly popular alternative minimally invasive approach. Advocates of each technique claim its superiority, but the issue has yet to be resolved and conclusions are complicated by the existence of a lateral (LRA) and true posterior (PRA) RA. Methods: A literature search was performed for all comparative studies of RA versus LA. Meta-analysis was performed according to PRISMA guidelines. Odds ratios and standardized mean differences (SMD) were used to compare dichotomous and continuous outcomes respectively. Results: Twenty-two studies were included, reporting on 1257 LAs, 471 LRAs and 238 PRAs. Both PRA and LRA were associated with a reduced length of hospital stay: SMD-1·45 (95 per cent confidence interval-2·76 to-0·14) and-0·54 (-1·04 to-0·03) days respectively compared with LA. Interstudy heterogeneity was present throughout the comparisons of hospital stay. When considering only the two randomized clinical trials (RCTs) there was no statistically significant difference in this outcome. One RCT, however, found a reduction in the median time to convalescence of 2·4 weeks in the LRA group. There were no differences in duration of operation, blood loss, time to ambulation and oral intake, or complication rates between techniques. Conclusion: RA overall has equivalent outcomes to LA but may be associated with a shorter hospital stay.