We conducted an overseas mobile clinic in Lao PDR and examined the results of biochemical tests and blood examinations. For the biochemical tests, we used a method involving plasma skimming film and filter paper, called “plasma separation plate.” In this study, we report the usefulness of the plasma separation plate, which is a newly developed method for the screening of biochemical tests in Japan. We were able to apply this method in a mobile clinic in Lao PDR. The quantitative concentration of plasma from blood collected from pricked fingers was measured by this method. Using the plasma skimming film and filter paper, the non-cell components in the blood were separated, and a quantity of the plasma was adsorbed by filter paper. Neither elaborate equipment nor electricity was required. The results of our test data indicated that few inhabitants suffered from adult diseases for which we were screening. We concluded, therefore, that this method is suitable for use in mobile clinics in the rural areas of developing countries.