MEGA (Molecular Evolutionary Genetics Analysis) is a software package designed for molecular evolutionary genetics analysis, specifically for IBM and IBM-compatible personal computers. It provides an interactive, user-friendly platform for estimating evolutionary distances, reconstructing phylogenetic trees, and computing various statistical quantities relevant to molecular evolution. The software is available for a nominal fee to cover production costs, but it is free for those unable to pay. MEGA includes methods for nucleotide and amino acid substitution distances, as well as synonymous and nonsynonymous substitutions, and offers options for handling alignment gaps and missing data. The manual covers installation, input data formats, basic sequence statistics, distance estimation methods, and guidelines for choosing appropriate distance measures. MEGA does not include sequence alignment methods or extensive options for maximum likelihood or parsimony methods, focusing instead on facilitating extensive sequence data analysis from an evolutionary perspective.MEGA (Molecular Evolutionary Genetics Analysis) is a software package designed for molecular evolutionary genetics analysis, specifically for IBM and IBM-compatible personal computers. It provides an interactive, user-friendly platform for estimating evolutionary distances, reconstructing phylogenetic trees, and computing various statistical quantities relevant to molecular evolution. The software is available for a nominal fee to cover production costs, but it is free for those unable to pay. MEGA includes methods for nucleotide and amino acid substitution distances, as well as synonymous and nonsynonymous substitutions, and offers options for handling alignment gaps and missing data. The manual covers installation, input data formats, basic sequence statistics, distance estimation methods, and guidelines for choosing appropriate distance measures. MEGA does not include sequence alignment methods or extensive options for maximum likelihood or parsimony methods, focusing instead on facilitating extensive sequence data analysis from an evolutionary perspective.