Sabah, one of the thirteen Malaysian states, is located in the northern part of Malaysian Borneo. It is a melting pot of many different cultures and traditions, being home to about 2.9 million people with more than 30 ethnic groups. It is also known as one of the twelve mega-diversity sites in the world with its rich living heritage, ethnic makes it ideal for the ecotourism industry. Sabah enjoys a steady flow of eco tourists from domestic and international markets with a gradual increase in the number of visitor arrival each year. Sabah‟s ecotourism is categorized by its natural attraction, wildlife, and wilderness habitats. This paper sets out to interpret and develop the indicators for success ecotourism sites in Sabah and measures its‟ development stage. The long-term viability of tourism can be assured only when the limitations and favorable opportunities of the overall environment for tourism development are understood and ways to measure changes induced by tourism are identified and applied. This thesis applied qualitative methods which can help researchers to understand how and why such behaviors take place. The data were then analyzed to get the results, which are success indicators of ecotourism sites based on the perception of stakeholders. There are two set of the indicators are proposed. The indicators are quite consistent with those others drawn from the literature review. The analysis also shows that there are issues that need to be addressed with regards to these indicators. These indicators are output-based; therefore there is a need to establish the measurement or the parameters of these indicators to make it more quantifiable and more meaningful. Another aspect that the thesis identified is that the success level of each ecotourism site. Different development level of the ecotourism sites will use different strategic in their management. In the end of the thesis, the level of sites development will linked to the Butler‟s Model in determine the success level of the ecotourism sites. This will contribute to tourism literature by enhancing the knowledge of ecotourism, and to the ecotourism industry by providing a means of ecotourism success.