Summary In spite of the much shorter thawing times, the use of microwave devices for heating units of fresh frozen plasma is still being discussed. Concerns about general and localised overheating are the main arguments against the use of microwave devices. We evaluated the warming of fresh frozen plasma using the recently introduced Transfusio‐therm 2000® microwave blood warmer. Units of fresh frozen plasma were weighed and the heating times were recorded. The surface temperature of the fresh frozen plasma bags during heating was recorded every 10 s. Temperature variation on the surface was examined by measuring the difference between peripheral and centrally placed temperature sensors. After heating, plasma temperature was determined using a calibrated thermometer. There were no signs of overheating during the heating process. The surface temperature of three units of fresh frozen plasma heated simultaneously (n = 45) was 34.0°C (SD, 1.5°C) after a mean heating time of 23.2 min (SD, 1.1 min). The mean (SD) temperature difference was −0.6 (0.5)°C and the mean (SD) plasma temperature was 33.6 (0.8)°C. Heating one fresh frozen plasma unit at a time (n = 20), the mean (SD) heating time was 6.3 (0.4) min. The surface temperature after heating was 34.3 (0.2)°C, the mean (SD) temperature difference was −0.6 (0.4)°C and the mean (SD) plasma temperature after heating 33.1 (0.6)°C. We conclude that no general or localised overheating of fresh frozen plasma occurs during or after heating with the microwave blood warmer.