In This study, according to the guidelines of PRISMA, the meta-analysis on prevalence of Streptococcus   species in horses with respiratory tract infections was performed. After compete search, data extraction and selection of studies, data were analyzed using comprehensive meta-analysis. The results of meta-analysis of selected studies were 95% confidence intervals, effect size, heterogeneity, weight, and publication bias. A total of 1831 (32.25 %) out of 5678 diseased horses in 20 study with upper respiratory symptoms were found positive for Streptococcus species. The final meta-analysis model of the size effect and null test at fixed and random effect showed the effect has a Z-value of -3.371 (P-value = 0.001) as opposed to the fixed effect's Z-value of -26.024 (P-value = 0.000). The degree of heterogenicity revealed Q-value (926.104), I-squared (97.948), P-value (0.000), and the Tau-squared of 0.989 with a 0.519 Standard Error are the final heterogeneity variables. Egger's linear regression test for asymmetry did not indicate publication bias, intercept (-0.53), 95% confidence interval (-6.45- 5.39), t-value (0.18), df = 18. The 1-tailed P-value is 0.426, and the 2-tailed P-value is 0.852.  The outcome of Kendall's tau with continuity correction (-0.00526), with a 1-tailed P-value of 0.487 and 2 -tailed P-value of 0,974. Duval and Tweedie's trim-and-fill method (only one study trimmed at the left side) resulted in an adjusted correlation from − 0.857 to − 0.737 with 95% CI: − 1.345 to − 0.428. The results of the present study indicate the association of Streptococcus species with clinical upper respiratory signs in horses.