This cross-sectional experimental study developed a methodology to analyze the cost-effectiveness of three malaria diagnostic models: microscopy; on-site OptiMALâ; and on-site Immunochromatographic Test (on-site ICT), used in remote non-microscope areas in Thailand, from both a public provider and patient perspective. The study covered six areas in two highly malaria endemic areas of provinces located along the Thai-Myanmar border. The study was conducted between April and October 2000, by purposively recruiting 436 malaria suspected cases attending mobile malaria clinics.  Each patient was randomly selected to receive service via the three diagnostic models; their accuracy was 95.17%, 94.48% and 89.04%, respectively. In addition, their true positive rates for all malaria species were 76.19%, 82.61% and 73.83%; for falciparum malaria 85.71%, 80.95% and 80.00%, and for vivax malaria 57.14%, 100% and 50%, respectively, with the parasitemia ranging from 80 to 58,240 µl of blood.  Consequently, their costs were determined by dividing into provider and consumer costs, which were consequently classified into internal and external costs.  The internal costs were the costs of the public providers, whereas the external costs were those incurred by the patients. The aggregate costs of these models were 58,500.35, 36,685.91, and 40,714.01 Baht, respectively, or 339.53, 234.39, and 243.93, in terms of unit costs per actual case. In the case of microscopy, if all suspected malaria cases incurred forgone opportunity costs of waiting for treatment, the aggregate cost and unit cost per actual case were up to 188,110.89 and 944.03 Baht, respectively.  Accordingly, the cost-effectiveness for all malaria species, using their true positive rates as the effectiveness indicator, was 446.75, 282.40, and 343.56 respectively, whereas for falciparum malaria it was 394.80, 289.37 and 304.91, and for vivax malaria 595.67, 234.39 and 487.86, respectively. This study revealed that the on-site OptiMALâ was the most cost-effective. It could be used to supplement or even replace microscopy for this criteria in general. This study would be of benefit to malaria control program policy makers to consider using RDT technology to supplement microscopy in remote non-microscope areas.