Objective: To systematically assess the prognostic difference between synchronous bilateral breast cancer (SBBC) and asynchronous bilateral breast cancer (ABBC). Methods: The relevant studies were collected by searching the national and international online databases. After literature screening, quality assessment and data extraction, Meta-analysis was performed by using RevMan 5.3 software. Results: Seven studies were finally included, involving 711 patients, with 225 SBBC cases and 486 ABBC cases. The results of Meta-analysis showed that the 1-, 5- and 10-year survival rates in SBBC patients were significantly lower than those in ABBC patients (OR=0.41, 95% CI=0.22–0.77, P=0.005; OR=0.52, 95% CI=0.39–0.69, P<0.00001; OR=0.43, 95% CI=0.25–0.74, P=0.003). Conclusion: The prognosis of SBBC is probably poorer than that of ABBC under the same medical circumstances and, however, further complete evaluation remains to be done.