The purpose of this research was to estimate the effect of recreation specialization on environmental attitudes of people climbing the top 100 peaks of Taiwan (shortened as, 100 peak climbers). The participants should have at least one experience of climbing the Top 100 Peaks of Taiwan. Using convenience sampling, the participants were from the domestic mountaineering community or club members. The number of valid questionnaires was 386. The results indicated there were differences among demographic variables, recreation specialization and environmental attitudes for 100 peak climbers. Also, there were correlation between recreation specialization and environmental attitudes while recreation specialization could positively predict the participants' environmental attitudes. The findings were as follows: the higher the level of recreation specialization for 100 peak climbers, the more positive environmental attitudes they had. In the end, the future research direction and practical implication are also recommended.