BACKGROUND: Climate change affects human health in various ways. Health planners and policy makers are increasingly addressing potential health impacts of climate change. Ethiopia is vulnerable to these impacts. Assessing students' knowledge, understanding and perception about the health impact of climate change may promote educational endeavors to increase awareness of health impacts linked to climate change and to facilitate interventions. METHODS: A cross-sectional study using a questionnaire was carried out among the health science students at Haramaya University. Quantitative methods were used to analyze the results. RESULT: Over three quarters of the students were aware of health consequences of climate change, with slightly higher rates in females than males and a range from 60.7% (pharmacy students) to 100% (environmental health and post-graduate public health students). Electronic mass media was reportedly the major source of information but almost all (87.7%) students stated that their knowledge was insufficient to fully understand the public health impacts of climate change. Students who knew about climate change were more likely to perceive it as a serious health threat than those who were unaware of these impacts [OR: 17.8, 95% CI: 8.8-32.1] and also considered their departments to be concerned about climate change (OR: 7.3, 95% CI: 2.8-18.8), a perception that was also significantly more common among students who obtained their information from the electronic mass media and schools (p < 0.05). Using electronic mass media was also significantly associated with knowledge about the health impacts of climate change. CONCLUSION: Health sciences students at Haramaya University may benefit from a more comprehensive curriculum on climate change and its impacts on health.