Alteration in animal behavior both during and after microwave irradiation is well documented. The report reviews a number of experiments in which specific behavioral effects in laboratory rodents were quantitatively changed by aspects of the exposure such as ambient air temperature, duration of the exposure, and orientation in the field while exposure parameters of 2450 MHz (CW) electromagnetic radiation were kept constant. Operant response rates were reduced and response durations were increased after overnight irradiations with 10 or 15 mW/sq.cm. when ambient air temperature during the exposure was 28 C but not when the temperature was 22 C. Operant behavior of rats which was reduced by 50% or more after an overnight irradiation was not reduced after a similar exposure of only 55 min. In another experiment, response rates declined with time after exposures lasting 4 hrs., did not decline further after exposures lasting from 4 to 8 hrs., but did decline further after exposures lasting longer than 8 hrs.