This paper examines the trends and potential of eco-tourism development in the Uttarakhand Himalaya by analysing both the potential of eco-tourism development and eco-tourism resource base. Data were gathered from the Uttarakhand Forest Statistical Diary 2017-18 and the Uttarakhand Eco-Tourism Corporation, Dehradun, respectively. The trends of eco-tourists' inflow in NPs and WLSs and revenue earned from it were examined. The key results from the data analyses depict that the Uttarakhand Himalaya has plenty of eco-tourism resource bases – six national parks (5006.76 km2), seven wildlife sanctuaries (2683.73 km2), and four conservation reserves (212.54 km2) along with rich faunal, floral, and avifaunal diversity. These resource bases have significant potential for eco-tourism development. The trends of eco-tourists' inflow in the NPs and WLSs are increasing, mainly domestic tourists (r2= 0.941). However, in comparison to natural and pilgrimage tourism, eco-tourists' inflow is low. In terms of the annual growth rate of eco-tourists' inflow, it has been decreasing (r2=0.168). The main reasons for decreasing growth rate of eco-tourists' inflow were remoteness, fragile landscape, rugged terrain, geo-hydrological hazards, lacking infrastructural facilities – transportation, accommodation, and institutional support in eco-tourism destinations. This study recommends policy measures for eco-tourism development in the Uttarakhand Himalaya through the creation of eco-tourism circles, development of eco-tourism parks, and providing adequate infrastructural facilities – transportation, accommodation, institutions, and communication. Keywords: Eco-tourism, national parks, wildlife sanctuaries, trends, eco-tourists' inflow, Uttarakhand Himalaya.