Introduction: the aim of this study was to investigate the putative hereditary pattern related to the presence/ absence of the palmaris longus muscle (PLM) in humans. Materials and Methods: we analyzed 99 individuals (56 women and 43 men) from 25 families living in the city of Jataí, southwestern of Goiás State, Brazil, who agreed to participate in the study by signing an approved consent form according to the University Research Ethical Committee. The tests to detect the presence/absence of PLM were performed in all subjects in both forearms by clinical examination. A careful analysis of all families phenotypes studied was performed. Results: Bilateral presence of PLM was detected in the majority of the population studied (75.76%). The unilateral absence of PLM was observed in 14.14% of subjects and bilateral absence in 10.1%. In 14 families both parents and 25 children had bilateral PLM and one child had unilateral absence of PLM. Parents Families (n=9) where one parent showed bilateral presence and the other unilateral/bilateral absence were observed children with both bilateral presences, unilateral or bilateral absence of PLM. Cases where both parents showed unilateral absence of PLM with children showing bilateral absence or presence of PLM were also observed. Conclusion: The presence of PLM appears to be dominant over its absence. It is suggested that the genotype for the absence of muscle is recessive while for the presence is dominant but with variable expressivity for the phenotype of unilateral or bilateral presence of the muscle.