Conduction and convection are assumed to account for most of the energy loss from the dead body to the (cooler) environment. There are no quantitative estimations in the literature for the contribution of radiation to heat loss. The aim of the present paper was to estimate the radiation energy loss in postmortem cooling. The Stefan-Boltzmann law is used and combined with a single-exponential model for the cooling process of the skin derived from experimental data of Lyle and Cleveland (1956). The influence of various factors (e.g. skin temperature, environmental temperature, body mass and body height) on the amount of radiation emitted was investigated. The radiation energy is quantitatively described as a function of time. The radiation energy loss ranged from approximately 200 kJ in small (165 cm) and lean (50 kg) bodies at room temperature (20 degrees C) to approximately 600 kJ in tall (185 cm) and over-weight (100 kg) bodies at outdoor temperature (5 degrees C) in the first hour postmortem.