Methylene blue (MB), a compound used in the treatment of malaria until the 1950s, now is under consideration as an alternative in fighting drug-resistant malaria parasites due to its deleterious effect on asexual and sexual stages of Plasmodium species. Its transmission-blocking potential has been demonstrated in vivo using murine malaria models such as P. berghei and P. yoelii and with P. falciparum through in vitro studies and clinical trials. On P. vivax parasites, MB studies have illustrated its high efficacy against the asexual stages. In contrast, there is a paucity of information about MB’s activity towards the sexual stages of P. vivax, and thus its inherent impact on transmission-blocking remains unknown. Here we report our findings on the antiplasmodial potential of MB against both sexual and asexual stages of P. vivax. To achieve this, we performed an ex vivo schizont maturation assay (SMA) ranged from 0.1 to 51.2 nM (MB) and 1.95 to 1000 nM of chloroquine (CQ) (control drug), an ex vivo zygote to ookinete transformation assay with a MB final concentration of 10 μM, a direct membrane feeding assay (DMFA) and a standard membrane feeding assay (SMFA) using a culture of P. vivax blood patient with minimum of 10% of gametocytes until 6 hours of MB exposure. In DMFA and SMFA were tested three MB concentration: 5, 10 and 20 μM. Corroborating with previous findings, MB inhibited P. vivax ring to schizont maturation (IC50 = median of 1.3 ƞM and range 0.01 to 18.4 ƞM). The control drug CQ demonstrated IC50 = median of 29.3 ƞM and range 10.4 to 72.7 ƞM. The MB compound also inhibited zygote to ookinete transformation ex vivo (mean inhibition of 76.5± 12.8%). From the DMFA experiments, MB did not affect infection rate (Control – 81%, 5 μM – 56.7%, 10 μM – 56.8% and 20 μM – 56.6%) however demonstrated a slight transmission-blocking activity as exhibited by a small decline in the infection intensity (number of oocysts per midgut) compared to the controls in all concentration tested. In contrast, the SMFA experiments demonstrated MB’s great impact in the infection rate (Control 0h – 72%, Control 6h culture – 65,7%, 5 μM – 8.4%, 10 μM – 2.8% and 20 μM – 0.0%) showing a total blockade of transmission in the highest concentration. The infection intensity was also impacted in all concentrations compared to the control. Additional studies are still necessary to determine that MB indeed blocks transmission in P. vivax. However, the data presented here corroborate the results in other malaria species and point to a promising drug for the treatment of all stages of P. vivax.