An in-house membrane dot-blot enzyme-linked immunosorbent assay kit, for the detection of specific antibody to a 31 kDa protein of Parastrongylus cantonensis was evaluated in a blinded multi-laboratory study. The kit was provided to technologists, who were trained in its use, from nine regional laboratories of Thailand. With an identical set of 20 coded serum samples and reference positive and negative controls, the kit was found to have a diagnostic sensitivity of 100% and a diagnostic specificity of 100% in all the laboratories. There was no obvious variation in quality among five lots of the antigen-coated nitrocellulose strips evaluated. The shelf life of the kit was > or = 6 months when the test components were stored at 4 degrees C and 18 months at -20 degrees C. The enzyme-linked immunoassay dot technique is easy to perform and does not require sophisticated electrical equipment; the result is available within 3 hours. If appropriate technical training is included, the application of this dot-blot ELISA kit in clinical laboratories throughout Thailand should be possible.