White-tailed and mule deer sera from North Dakota were tested for the presence of neutralizing titers against 15 different arboviruses. Positive reactions in both species were obtained to eight viruses, five of which had not been previously recognized in the state. There was no significant difference (Chi square P.05) in the reactor levels of the two deer species to any of the viruses. Geographically, three of the viruses appeared to be limited to western North Dakota, while the other five were detected statewide.