It has been previously demonstrated by us that microwave irradiation at 2450 MHz causes diffusion of dopamine from rat brain regions of high dopamine concentration to contiguous regions low in dopamine. Because we have found that the heating pattern at 986 MHz is opposite to that seen at 2450 MHz, we attempted in the present study to eliminate DA diffusion by heating at 986 MHz. However, dopamine levels were elevated in frontal and parietal cortex, remainder of cortex, and amygdala after sacrifice by microwave irradiation at 986 MHz. Norepinephrine levels were unaffected by sacrifice method. Microwave-induced diffusion of certain substances must be considered in the interpretation of regional neurochemical data.