SIMHYB is a Java-based software for the simulation of mixed hybridizing populations. The program is intended for the analysis of the effect of the different demographic and adaptive parameters on the evolution of these populations. Census size of each species, number of intermediate specific classes, directional fertility among them and fitness coefficient of each class can be defined by the user. Inheritance of fitness and ageing effect are also taken into account. The software generates individuals of known pedigree, allowing their traceability throughout the generations.