The in vitro alternative assay for evaluating skin sensitizing potentials (SSP) called human Cell Line Activation Test (h-CLAT) has been recently adopted as an international test guideline. The present study was proceeded to pursue the domestic establishment and expansion of h-CLAT. The standard operational procedure was prepared in detail by the lead laboratory (LL) and transferred to one participating laboratory (PL). The LL demonstrated technical proficiency for the 10 substances listed in OECD TG 442E. The PL also demonstrated a certain level of proficiency, in that 4-phenylenediamine and 4-aminobenzoic acid distributed with coded names were correctly classified as positive and negative on SSP, respectively, and other indices including 75% cell viability (CV75) and relative fluorescence intensity (RFI) % for CD54 and CD86 were fell within the reference range. Methyl methacrylate, nickel chloride, and resorcinol, which are inconsistent in predicting SSP through various alternative test methods, were unanimously predicted as negative, positive, and positive on SSP by the two laboratories for the first time through h-CLAT. Both chlorobenzene and sodium lauryl sulfate with the existing h-CLAT report as positive and negative, respectively, were predicted as negative by the PL, which could contribute toward overall categorization into non-skin sensitizer.