Genetics, genetics x environment (GGE) biplot analysis is an effective method, based on principal component analysis, to fully explore multi-environment trial data. It allows visual examination of the relationships among the test environments, genotypes, and the genotype x environment (GxE) interactions. Data from multi-environment trials of 'P. radiata' D. Don containing 165 to 216 families in five environments were used to demonstrate the results and application of GGE biplot analysis. There were non-overlapping clusters of two and three sites, which indicated two distinct environments. The best family for both of the distinct environments was also identified. Genetic correlations among sites ranged from 0.98 to -0.50, indicating that there were large GxE interactions among the test environments.