Objective: To determine the efficacy of Tongkat Ali (Eurycoma longifolia) herbal extract on erectile function improvement. Methods: Comprehensive electronic databases were searched from inception through October 2014. Randomized controlled trials investigating Tongkat Ali compared to placebo were included. Outcome of interest was the improvement of erectile dysfunction. The difference of changes from baseline of the outcome between Tongkat Ali and placebo was pooled using weighted mean difference (WMD). Methodological quality of included studies was assessed using Jadad s quality scale and Cochrane s risk of bias. Results: Of the 342 articles identified, 2 studies involving a total of 139 participants were analyzed. No significance between group difference was found in the mean WMD of the change in the 5- item version of the international index of erectile function (IIEF-5) at week-12 (0.91; 95 CI: -1.50 to 3.33 with I2=89.5 , P-value=0.002) with statistical heterogeneity. Based on the subgroup analysis, significant improved IIEF-5 score of 2.15 (95 CI 1.03-3.27) was found in subjects with lower baseline IIEF-5 score, but this was not seen among those with higher baseline IIEF-5 score. Conclusion: Based on current evidence, the herbal extract of Tongkat Ali may have clinical effect on erectile function. However, more efficacy trials are warranted to further support current evidence.