[en] UFOMOD and MESOS are compared concerning the calculated airborne concentrations of noble gases, quantities of radionuclides deposited, or the fractions of radionuclides remaining in the atmosphere, respectively, as well as calculated ground-level contamination due to Cs-137 and I-131 at well-defined locations at different distances and directions from the point of release (MESOS) and at well-defined locations at different distances averaged over all directions of transportation (UFOMOD) (height of release 10 m). On the average, the mean airborne concentration and ground-level contamination differ by a factor less than five. If one compares - integrated overall deposited by dry deposition only without considering wet deposition during transport and vice versa integrated over all dispersion directions (MESOS and UFOMOD) considerable differences emerge between the models, especially concerning the calculation of wet deposition. Here, differences amount to a factor of two. However, if, in addition the probability of a location being exposed is also taken into account, the model differs by factors up to 10 at selected locations. It is shown how UFOMOD calculations can be improved and adapted to reality by additional information from MESOS calculations. (orig./HP)