Background: Findings about the effect of prophylactic antibiotics in preventing genital tract infection (GTI) associated with surgical procedures used for incomplete abortions are conflicting. Some reported a decrease in infection associated with the use of antibiotic prophylaxis, whereas others found no significant reduction in GTI. Objective: To synthesise systematically the evidence on the effect of prophylactic antibiotics compared with placebo in women undergoing surgical procedures for incomplete abortion. Search strategy: In February 2020, PubMed, Embase and Cochrane Central for Register of Controlled Trials were searched for relevant published randomised controlled trials. Selection criteria: Randomised controlled trials reporting GTI following surgical procedures for incomplete abortion and comparing antibiotic prophylaxis with placebo. Data collection and analysis: Meta-analysis using inverse variance heterogeneity model included subgroup and sensitivity analyses determined a priori were conducted. The quality of evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE). Main results: A total of 16 178 women who participated in 24 eligible randomised controlled trials published between 1975 and 2019 were included. Pooled estimates showed the risk of GTI following surgical procedures after incomplete abortion was significantly lower among those who had prophylactic antibiotics (relative risk [RR] = 0.72; 95% CI 0.58–0.90; I2 = 49%). There was no significant effect of antibiotics in women in low- and middle-income countries (three studies, 3579 participants, RR = 0.90; 95% CI 0.50–1.62; I2 = 63%), but it was clinically and statistically significant among women high-income countries (21 studies, 12 599 participants, RR = 0.67; 95% CI 0.53–0.84; I2 = 44%), with a strong level of evidence as assessed by GRADE. Conclusion: This study provides evidence that antibiotic prophylaxis is beneficial in reducing post-abortion GTI among women undergoing surgical procedures for incomplete abortion. More studies are needed from low- and middle-income countries. Tweetable abstract: Prophylactic antibiotics after incomplete abortion are effective in reducing GTI. More studies are needed from low- and middle-income countries.