Blood samples were obtained from 70 European wild hogs (Susscrofa), of which 33 were live-trapped in the Great Smoky Mountains National Park and 37 were reared in captivity on farms geographically proximal to the mountains. Sera were analyzed for chloride, potassium, sodium, glucose, blood urea nitrogen, total serum protein, albumin, alpha, beta and gamma globulins. The albumin/globulin ratio was calculated. Data were analyzed for the effects of sex, age, and location by least squares analysis of variance. With the exception of semm sodium, significant sex differences were not found. With the exception of glucose, semm bio-roaming hogs were slightly higher than females. Among adult and subadult, free-roaming hogs, only the total senlm protein was significantly higher in the adults. Serum values ofmale and female pen-reared hogs were similar though the females had somewhat higher levels of total serum protein and albumin. Adult, pen-reared hogs had slightly higher levels of potassium, sodium and beta globulins and significantly higher levels of total senJm protein than subadults. Location (i.e., free-roaming versus pen-reared) had a significant influence on potassium, sodium, glucose, blood urea nitrogen, total serum protein, alpha, beta, and gamma globulins. The influence of sex was significant only on sodium levels. Age apparently exerted a significant influence on chloride, sodium, total serum protein, albumin, and the gamma globulins. It is postulated that the differences mentioned above may be largely accounted for by differences in hematopoietic development, differences in reaction to stress and excitement, and differences in locational milieu.