Isabel Province which is the study site of the researcher is the second largest province in the country. It is situated in the Northeastern part of Luzon. It covers four towns namely Ilagan, Cauayan, Santiago, Isabela and Reyna Mercedes. As "ethnobotany" implies, the concern of this was the identification of plants growing in the Gaddang area which are considered useful by the Gaddang people. The methods employed in gathering the data needed were the survey and the Field Laboratory, the former making use of both the Questionnaire and the Interview devices, and the latter involving both On-the-spot studies of useful plants with the use of Field Guide, as well as the Collection of Fertile Plant Specimen which were processed and mounted on herbarium sheets for further taxonomic study. From the variety of sources of data gathered the findings show a good picture of the Gaddang people and the nature of their immediate environment and their relation to the quality of Gaddang Flora vegatation has been contained. As furnished by the respondents and interviewees the lists of useful plants are as follows: There are 79 species and 35 families for food, 44 species and families for building materials, for furniture and household equipment there were 18 species and 9 families and for other purposes there were 53 species and 32 families. The role of plants in the Gaddang culture has revealed in the etymology of certain plant-names and also in various beliefs which has a plant-bearing has also been studied and investigated.