FSTAT (Version 1.2) is a computer program developed by J. Goudet to calculate F-statistics, which are used to assess genetic differentiation among populations. The program calculates various fixation indices, including $ F_{is} $, $ F_{it} $, $ F_{u} $, and a new index measuring Hamilton's relatedness. It also provides confidence intervals, tests for significance, and allows for the analysis of genetic distance between samples. The program is based on the estimators of Weir and Cockerham (1984) and includes features such as resampling methods, permutation tests, and handling of missing data. It is suitable for haploid data and can process large datasets with up to 200 samples, 50 loci, 99 alleles at the most polymorphic locus, and 5,000 individuals. The program is distributed freely and can be accessed electronically or via an FTP server. It is designed to avoid the limitations of existing tests, such as those based on chi-square statistics, by using permutation methods. The program is part of a research project on the evolutionary effects of gene flow and has been supported by various funding bodies. The program is written in Pascal and is compatible with different PC architectures. It uses a random number generator proposed by L'Ecuyer (1988) for its statistical procedures. The output format is compatible with many spreadsheet programs, facilitating data analysis and visualization.FSTAT (Version 1.2) is a computer program developed by J. Goudet to calculate F-statistics, which are used to assess genetic differentiation among populations. The program calculates various fixation indices, including $ F_{is} $, $ F_{it} $, $ F_{u} $, and a new index measuring Hamilton's relatedness. It also provides confidence intervals, tests for significance, and allows for the analysis of genetic distance between samples. The program is based on the estimators of Weir and Cockerham (1984) and includes features such as resampling methods, permutation tests, and handling of missing data. It is suitable for haploid data and can process large datasets with up to 200 samples, 50 loci, 99 alleles at the most polymorphic locus, and 5,000 individuals. The program is distributed freely and can be accessed electronically or via an FTP server. It is designed to avoid the limitations of existing tests, such as those based on chi-square statistics, by using permutation methods. The program is part of a research project on the evolutionary effects of gene flow and has been supported by various funding bodies. The program is written in Pascal and is compatible with different PC architectures. It uses a random number generator proposed by L'Ecuyer (1988) for its statistical procedures. The output format is compatible with many spreadsheet programs, facilitating data analysis and visualization.