A new approach to the reconstruction of dielectric properties of unknown biological bodies is proposed, which is developed starting from an integral equation formulation of the electromagnetic inverse scattering problem. A Gibbs Random Field model is used to develop a stochastic approach based on the Bayes theorem. An iterative solution is obtained by the simulated annealing technique. The method integrates the important features of the spatial domain method with the possibility of taking into account a priori information on the scatterers under test. No large ill-conditioned matrix inversions are required. A two-dimensional formulation is considered, involving cylindrical scatterers illuminated by transverse magnetic-wave incident fields. A multi-illumination multiview reconstruction process is also performed. Some results on the reconstruction of strong scatterers are reported.