Although several animal and human studies have investigated the effect of alpha-lipoic acid (ALA) on blood pressure (BP), these findings are inconsistent. This systematic review of randomized clinical trials was conducted to summarize the evidence on the effect of ALA on BP. PubMed, SCOPUS, and Google Scholar databases were searched based on MESH term (“Thioctic acid” in combination with “Hypertension” and “Blood pressure”) to identify related papers published up to December 2015. We summarized the results of the relevant studies in this review. In total, nine studies included in this review, seven parallel-designed trials and two crossover-designed trials. The results of parallel-designed studies are inconsistent. Five studies indicate no significant effects for ALA supplementation on BP, but two trials show effects on BP. Unlike parallel-designed trials, two crossover-designed trials have shown similar results and both report no effect for ALA on BP. Several studies investigated the effect of ALA on BP. Most of the papers show no significant effect for supplementation and the studies have shown that associations are limited. However, these findings are limited and there is a need for further and more accurate researches to be clarified.