Varicocele is the most common cause of male infertility. Varicoceles are classified into two types: clinical and subclinical varicoceles. Some researchers reported right subclinical varicoceles are often accompanied with left clinical varicoceles. However, the treatment is controversial. Our aim was to compare the clinical outcome of unilateral varicocelectomy (UV) and bilateral varicocelectomy (BV) in infertile males with left clinical and right subclinical varicocele. A total of four randomised controlled trials (RCT) were enrolled in this study, including 637 cases with left clinical and right subclinical varicocele (318 cases in the BV group and 319 cases in the UV group). The fixed effects model combined difference in progressive sperm motility between the two groups was 6.42% (95% CI: 5.09, 7.75). The random effects model combined difference in normal sperm morphology between the two groups was 2.04% (95% CI: 0.60, 3.48). The odds ratio shown by the fixed effects model in spontaneous pregnancy rate was 1.73 (95% CI: 1.24, 2.43). No statistically significant difference between the two groups was found in sperm concentration and sperm motility. Thus, BV may be superior to UV for infertile male patients with left clinical and right subclinical varicocele. However, more properly conducted RCTs are still needed.