A laboratory-based study was performed in order to assess the infestation capacity of the mosquito parasite nematode Romanomermis iyengari Welch, on Anopheles nuneztovari Gabaldón and Aedes aegypti L. For each mosquito species, nine hundred (900) I to III instars larvae were taken. These larvae were infested with pre-parasitic larvae of R. iyengari in proportions of 5:1 and 10:1. The infestation averages obtained were 3.9 and 6.7 for Anopheles nuneztovari, and 1.9 and 4.7 for Aedes aegypti respectively. Mortality ranked between 95 and 100% for both mosquito species and Anopheles nuneztovari showed the highest susceptibility to the nematode parasitism.