ESDU 97019 introduces a Fortran program@ supplied on disc in the software volume as source code@ that determines the equilibrium temperatures and heat flow rates in a network of heat conducting and dissipating parts. The thermal network analysis implemented by the program is quite general but is primarily intended for use with self-contained bearing assemblies such as dry rubbing and rolling element bearings@ fluid film bearings lubricated with oil or grease@ and oil-impregnated porous bearings. The program incorporates representations of standard parts@ such as shafts and bushes@ that can be combined to model the heat generation@ conduction and dissipation in the complete assembly. Networks of up to 99 of these parts with up to 99 nodal connections between them can be analysed by the program. The program allows the parameters of a part to be changed@ and modelling refinements to be incrementally added after examining results obtained using a simpler model. The manual method programmed is described in ESDU 78026 to 78029 and many of the data used there on the estimation of heat transfer@ for example@ from rotating shafts or across joints@ are presented in a form suitable for direct use with the program. A broad indication of the heat generation rates to be expected in bearings is also provided. The use of the program is fully described@ error messages that may appear are explained@ and its use is illustrated by worked examples of a rolling element bearing@ a commercial plummer block assembly@ and a ring-oiled hydrodynamically lubricated bearing assembly.