Abstract: In this study, we analyse alternatives for the parallelization of the simulated annealing algorithm when applied to the placement of modules in a VLSI circuit considering the use of PVM on an Ethernet cluster of workstations. It is shown that different parallelization approaches have to be used for high and low temperature values of the annealing process. The algorithm used for low temperatures is an adaptive version of the speculative algorithm. Within this adaptive algorithm, the number of processors allocated to the solution of the placement problem and the number of moves evaluated per processor between synchronization points change with the temperature. At high temperatures, an algorithm based on the parallel evaluation of independent chains of moves has been adopted. It is shown that results with the same quality of those produced by the serial version can be obtained when shorter length chains are used in the parallel implementations.