AbstractRabbit polymorphonuclear leucocytes (PMN, neutrophils) obtained from peritoneal exudate were exposed in vitro for one‐half or one hour to continuous wave or amplitudemodulated (20‐Hz) 100‐MHz RF radiation in a temperature‐controlled coaxial exposure chamber at field strengths from 2.5 to 4.1 V/cm (SARs of 120 to 341 W/kg). RF exposure at 37° 0.2°C had no detectable effect on PMN viability or phagocytosis compared to sham‐exposed cells simultaneously subjected to the same time‐temperature regime. Temperature control studies indicated that at 37°C no effect on PMN viability would be expected but phagocytosis would be reduced by approximately 6%/°C temperature increase. The absence of an effect of RF exposure suggests that there was minimal undetected intrasample heating and that phagocytosis was not affected by 100‐MHz RF radiation under the conditi