A multimode microwave (MW) exposure chamber was employed to investigate the effects of low-intensity CW radiation on one innate and two learned behaviors of female Sprague-Dawley rats. Relative to sham-irradiated controls, exposure to 2.45-GHz radiation at an averaged specific absorption rate (SAR) of 2.3 mW/g was associated with: (a) statistically significant increases in locomotor activity, (b) statistically reliable evidence of disrupted differential responding during tests of an appetitively reinforced operant behavior, but (c) no differential effects on the performance of a Sidman avoidance response. The observed effects emerged almost immediately following the onset of MW radiation and persisted throughout the course of a 22-week sequence of exposures to radiation. Periodic sampling of rectal temperature revealed no indication of whole-body elevation of temperature. The observed behavioral effects are consistent with a general activation hypothesis and, although the underlying mechanism remains unclear, suggest MW-induced alterations in function of the central nervous system.