A comparison of the Hymenoptera biodiversity in two Pinus pinaster stands located in Peninsula of Setubal (Portugal) was conducted. One of the stands was planted about 10 years ago, and the other one is a natural regeneration after a fire that occurred 18 years ago. The samples were obtained with two "Malaise" traps, installed in each stand. The collected Hymenoptera were identified up to the family level. In the superfamily Ichneumonoidea the insects were identified up to the subfamily and different species were separated. Data were compared and analysed by the Wilcoxon signed ranks test. Results indicate that at the family level, the abundance, richness and diversity (equitability and dominance) were significantly different between stands. The same results were obtained with Ichneumonoidea. It was also observed that in the present study, abundance, richness and equitability are positively correlated with the air temperature (p<0,05). Air humidity correlates negatively with abundance. The number of species present in the shrub layer and the number of flowering species correlate positively with abundance and richness. In Ichneumonoidea, only the air humidity, the number of species in the shrubs and the number of flowering species correlate with abundance, richness and equitability. none2001