A wetland is an ecosystem which is the most useful and highly-energetic transition area. This study has been carried out to develop the wetland function assessment methods and apply on the natural wetlands (Mul-young-ari wetland in Jeju-island and Bangdong wetland in Taejon Metropolitan city) using RAM (Rapid Assessment Method). The RAM is useful method for assessing the wetland functions in terms of general functions acquired by once or twice onsite surveying. Eight functions of 2-12 variables each are analyzed for assessing the wetland functions. The results are as follows : 1) The conservation values of two wetlands are "High". 2) In Mul-young-ari wetland, such functions as groundwater discharge, floral diversity and wildlife habitat, shoreline/stream bank protection are relatively high, but some functions such as flood/storm water storage, aesthetics and recreation are "Moderate" - "High". 3) In Bangdong wetland, such functions as floral diversity and wildlife habitat, groundwater discharge, flood/storm water storage, aesthetics and recreation are high, and another functions are "Moderate" - "High". The taxonomy of this study stems from assessing functions of inland wetlands using indices of RAM. So It is needed that consequent studies are to be performed with verifying the variables and indices.