The effects of atmospheric air pollution on some hematological and plasma parameters, activity, and food and water consumption in Apodemus sylvaticus (wood mouse) and Mus musculus (mouse) were studied. The studies were undertaken in the area of Cercs (polluted area in Spain), where there is a coal-fired power plant that emanates SO2, NOx, and particles, and the area of St. Jaume de Frontanyà (nonpolluted area), located 40 km from the area of Cercs, with similar climatology, relief, and altitude, but without air pollution. Apodemus sylvaticus were captured in the field and Mus musculus were placed in cages in both studied areas. The results showed that there is a significant decrease in hematocrit, and a significant increase in leucocyte number, mean corpuscular hemoglobin concentration, osmolality, and gamma-globulin in Mus musculus, and a decrease in albumin (%) and albumin/globulin index in Apodemus sylvaticus. A negative correlation between hematocrit values and pollution was found. In mice placed in cages in the polluted area a slight but significant decrease in water and food consumption, and slower activity, was observed. The results suggest that pollution could induce a decrease in water and food consumption, which may be due to an observed reduction in activity.