The northern cricket frog (Acris crepitans) is a resident of streams, rivers, and wet-lands of eastern North America. We documented abnormalities in A. crepitans housed in the Arkansas State University Museum of Zoology Herpetology Collection. Abnormality frequency increased from 1957 to 2000 (χ²=43.76, df=3, P<0.001). From 1957 through 1979 only 3.33% of specimens were unusual. This rate was 6.87% during the 1990s, and in 2000 it was 8.48%. High frequencies of abnormalities were identified in the following Ozark highland counties: Sharp, Lawrence, and Randolph. We observed 104 abnormalities among 1,464 frogs (7.10%). The differential abnormality frequencies observed between the Arkansas lowlands and highlands are striking. The Ozarks had significantly higher frequencies of abnormalities than other Arkansas regions (χ²=59.76, df=4, P<0.001). The Ouachita Mountains had significantly higher frequencies than the Gulf Coastal Plain, Delta, or Arkansas River Valley (χ²=13.172, df=3, P<0.01). There was no difference in abnormality frequency between the Gulf Coastal Plain, Delta, and Arkansas River Valley (χ²=0.422, df=2, P>0.70). Proposed hypotheses for distributions include: 1) A. crepitans might possess naturally high abnormality levels, and land use practices of the Delta may reduce this variability; 2) an unknown xenobiotic may be in Ozark streams causing increased numbers of abnormalities; 3) the museum's collection effort may be skewed; 4) Delta habitat might be more favorable for green tree frogs (Hyla cinerea) allowing this species to drive out A. crepitans through competition; here, abnormal metamorphs are not detected because they are even less competitive than normal individuals.