We report the natural co-infection of a single Anopheles mosquito with Plasmodium vivax Grassi & Feletti phenotypes VK210 and VK247. In total, 8,452 anopheline mosquitoes collected between June 1999 and July 2001 were tested by ELISA for the presence of circumsporozoite (CS) protein to VK210, VK247, and P. falciparum (Welch)(PF). A total of 29 species was represented; however, the predominant species tested were A. minimus Theobald (4,632), A. sawadwongporni Rattanarithikul & Green (1,248), A. maculatus Theobald (1,201), A. campestris Reid (478), and A. barbirostris Van der Wulp (391). A total of 17 positive mosquitoes was identified by ELISA, and included the following: A. minimus infected with VK210 (5), PF (3), and both VK210 and VK247 (1), A. maculatus infected with VK210 (1), VK247 (1), and both VK210 and VK247 (1), A. campestris infected with VK210 (2), A. sawadwongporni infected with VK247 (1) and PF (1), and A. hodgkini Reid infected with VK247 (1). This is the first report of a single mosquito naturally infected with both VK210 and VK247.