Four food borne pathogens (Listeria monocytogenes CA and Ohio(2), Salmonella enteritidis FDA and Salmonella typhinlurium E21274, Escherichict coli O157:H7 931 and 933, Staphylococcus aureus 485 and 765) were inactivated under mild temperature (60 degrees C) and their survival curves determined at selected time intervals. Tailing was observed in all survival curves as a monotonic upward concavity. The resulting survival curves were either described by the Weibull or traditional first-order model and goodness of fit of these models was investigated. Regression coefficients (R-2), root mean square error (RMSE) and correlation plots suggested that Weibull model produced a better fit to the data than the traditional model. Hazard plots suggested that the Weibull model was fully appropriate for the data being analysed. Although more studies should be carried out to evaluate the applicability of the nonlinear models, the present study has shown that thermal process calculations should most probably be reconsidered. This could lead to a reduction in under- and over-processing of thermally treated foods (c) 2006 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.