Field radiation monitoring and radionuclide analysis of soils were performed at various geological areas in Taiwan. The field-observed dose rate was 0.031-0.107 μGy h. The dose rate ascribed to naturally occurring radionuclides in soils that were geologically characterized varied from 0.002 to 0.079 μGy h. A linear correlation was observed between the activity-derived and field-observed dose, which indicated that the absorbed dose rate from the cosmic rays is almost constant (0.030 μGy h) throughout the flat area on the island.