Predictive biomarkers for early diagnosis of prostate cancer are important for its treatment. The functional microRNAs in the exosomes of plasma and serum samples are of interest as stable and non-invasive biomarkers for recurrence in cancer patients. The present study aimed to clarify the value of plasma exosomal mRNA-125a-5p and miR-141-5p miRNAs as biomarkers for the diagnosis of prostate cancer. The study included 19 healthy individuals and 31 prostate cancer patients. In comparison to the levels in healthy controls, exosomal miR-141-5p levels showed a slight increase in prostate cancer patients (P = 0.085), and miR-125a-5p levels that showed a significant decrease in patients with prostate cancer than in healthy controls (P = 0.032). As a derived parameter, the miR-125a-5p/miR-141-5p ratio was significantly higher in patients with prostate cancer than in healthy controls (P < 0.001). We found that exosomal miR-141-5p in plasma showed a promise in distinguishing prostate cancer patients with the AUC was 0.652, and for miR-125a-5p, the AUC was 0.691. For the miR-125a-5p/miR-141-5p ratio, the AUC value was 0.793. We found that miR-125a-5p has a weak positive correlation with PSA (correlation coefficient = 0.3413). Moreover, miR-141-5p has been found to hold a negatively no-significant correlation with PSA, with the correlation coefficient is -0.1102. We speculate that, as diagnostic markers for prostate cancer, miR-125-5p and miR-141-5p might be independent of the PSA. In summary, the results of this study suggest that high plasma exosomal expression of miR-141-3p and low expression of miR-125a-5p in plasma exosomes from prostate cancer patients might be useful markers of specific tumor traits associated with prostate cancer. Moreover, the miR-125a-5p/miR-141-5p ratio seems to perform better than either of the single values alone.