Instrumental neutron activation analysis (INAA) was used in the homogeneity study of a Perna perna (Linnaeus 1758) mussel reference material. Simultaneous determination of 15 elements in six bottles of the material, from
a total of 171, was performed. The bottles were considered homogeneous for the analyzed elements, at the 95% confidence level,
according to the analysis of variance test performed. Elements were also determined in one bottle with five different sample
masses for minimum sample intake estimation. Results varied from 50 to 350 mg, depending on the element.