The aim of this study was to examine the validity and reliability of a novel immunoassay, developed to assess salivary Immunoglobulin A (s-IgA). Validity and reliability of the Individual Profiling Lateral Flow Device (IPRO LFD) for s-IgA concentrations ([s-IgA]) was assessed in males (n = 12) and females (n =13) who were involved in recreational activities. Reliability of the IPRO LFD method was assessed by comparing [s-IgA] of two saliva samples collected concurrently, while validity was assessed by comparing with an enzyme-linked immunosorbent assay (ELISA) method. The IPRO LFD had a strong positive correlation (r = 0.93, p < 0.001), with no difference in [s-IgA] compared with the ELISA. The IPRO LFD was considered reliable (ICC r = 0.89, p < 0.001 and CV = 9.40 %) for measures of [s-IgA]. We concluded that the IPRO LFD method may be a substitute to the ELISA method for measurements of [s-IgA].