Blood and feces were collected from 34 adult (19 males, 15 females) and seven juvenile (three males, one female, three not reported) free-ranging coyotes (Canis latrans) on the US Department of Energy's Savannah River Site (South Carolina, USA). Significant (P<0.05) hematologic differences by sex were noted for red blood cell counts, hemoglobin, and hematocrit. Biochemical differences by sex occurred only for albumen (P<0.05). Twenty-one adults were antibody positive for at least one of four viruses: canine adenovirus type 1 (CAV-1; 68%), West Nile virus (WNV; 60%), Eastern equine encephalitis virus (EEEV; 38%), and Canine distemper virus (CDV; 15%). Of the seven Leptospira serovars tested for, seven (25%) of 28 adults were positive for one or more of five serovars: Pomona, Grippotyphosa, Icterohaemorrhagiae, Bratislava, and Autumnalis. Three (43%) of seven juveniles had seropositivity for a virus, one each for CDV, CAV-1, and WNV. No juveniles were seropositive for EEEV or any of the seven Leptospira serovars. Blood smears of 12 adults were positive for Dirofilaria immitis microfilaria, but blood smears from all juveniles were negative. Parvovirus was identified by electron microscopy from the feces of one adult. Ancylostoma spp., Trichuris spp., and Isospora spp. were observed in fecal samples. These data may aid in understanding the role of coyotes in disease ecology.