A study to determine the species diversity of Anopheles and Culex mosquitoes was carried out in Makurdi in April, 2014. A total of 200 adult mosquitoes, representing two genera, were collected from four locations within the study area by Pyrethrum Spray Catches and Net Traps. The mosquito samples were identified using standard keys and Polymerase Chain Reaction. Morphological identification revealed three main species: Culex quinquefasciatus 105 (52.5%)>Anopheles gambiae complex 68 (34.0%)>Anopheles funestus complex 27 (13.5%). PCR confirmed two Anopheles gambiae sibling species as Anopheles gambiae s.s. 36 (52.9%) and Anopheles arabiensis 26 (38.2%) while 6 (8.9%) of the Anopheles gambiae complex did not amplify. Meanwhile, Multiple Comparison using Least Significant Difference showed no significant difference (P>0.05) between the occurrence of Anopheles gambiae s.s. and Anopheles arabiensis. However, the result revealed a significant difference (P<0.05) between the abundance of Culex and Anopheles species collected from the Makurdi area. The study showed that Anopheles and Culex mosquitoes abound in the study area with potential consequences in the transmission of Plasmodium species (malaria) and Wuchereria bancrofti (Lymphatic filariasis). The findings were intended to provide data on mosquito species diversity in the study area that would be useful in any future vector control interventions.