There has long been the requirement for a marker of well being and chronic stress that is, itself, unaffected by the transient stressors associated with sampling. Work done in the human, the rat and the dog suggests that salivary IgA may fulfil these criteria. This is the first report on the establishment of a saliva sampling technique and immunoelectrophoretic assay for quantification of secretory Immunoglobulin A (s-IgA) in the squirrel monkey (Saimiri sciureus). A safe and effective sampling method is described, as well as a detailed description of an accurate rocket immunoelectrophoretic assay developed for this study. Preliminary results demonstrate a large intra-individual variation, as well as inter-individual variation in s-IgA levels between successive days. This indicates that if stress is associated with decreased s-IgA levels in the squirrel monkey, the usefulness of s-IgA as a stress marker may be limited because analyses of large numbers of samples may be necessary in order to obtain significance.