Purpose: Nature-based tourism is one of the largest and fastest growing areas contributing to the growth of the world tourism industry. It is also a form of tourism appealing for (almost) of tourists from all generations. But the particular characteristics of each generation influence their attitudes and behaviors. Within this, and based on the two dominant attitudes to nature, anthropocentrism and ecocentrism, the purpose of the study is to measure the attitudes toward Nature of nature-based tourists through different generations. Originality: Given the growing research of Nature-based tourism and of generations and travel behavior, there is no study that measures the ecocentric and anthropocentric attitudes toward Nature of Millenials, Generation X and Baby Boomers nature-based tourists. Methodology: A quantitative research was design for this study, relying on a questionnaire comprising of 8 question-statements adapted from instruments used previously in related studies. Questionstatements were answered on a 5-point Likert scale, with 1 referring to strongly disagree and 5 referring to strongly agree. The questionnaire was applied to 315 domestic and international tourists - 105 Millennials, 105 Generation X and 105 Baby Boomers - who visit Natural Parks in 2017 and 2018. Findings: The results indicate that the Millenials and Baby Boomers' tourists are more ecocentric regarding Nature than the tourists of Generation X, which reveals a more anthropocentric attitude. Pratical Implications: The findings suggest that there are differences on people's attitudes toward Nature based on the generations' cohorts, which could be useful to Nature-based destinations managers particularly to design, develop and implement a strategy of Sustainable Tourism.