OBJECTIVE: To assess the knowledge and perception of parents of high school students about the health effects of environmental hazards in Sakarya province of Turkey. METHOD: The cross-section study was conducted in May 2009 in which randomly assigned 362 parents answered a questionnaire inquiring about the sociodemographics and a list of environmental hazards such as tobacco smoking, sunlight exposure and skin cancer, global climate change, air pollution, noise exposure, smoking during pregnancy and low birth-weight, exposure to radon and lung cancer, reducing radon, air pollution and cardiovascular diseases, base station and childhood leukaemia, extremely low frequency electric and magnetic fields and brain tumour.The participants were also asked about water pollution, environmental tobacco smoke, air pollution, ozone depletion, exposure to radon gas, soil pollution, noise pollution, formaldehyde related with furniture, ground ozone and pesticides etc. SPSS 15 was used for statistical analysis. RESULTS: Among the participants 226 (62.4%) were females, and 284 (78.5%) were in the 31-45 age group. There were 246 (68%) high school or university graduates. Of the participants, 357 (98.6%) knew that smoking was a health risk, but exposure to radon gas was not that prevalent (n=194; 53.6%). The most intimidating risk was claimed as unsafe water (n=311; 85.9%), while noise exposure was the least source of worry among the environmental risks (n=134; 37.0%). CONCLUSION: There is a necessity to inform the public about less-known but significant environmental risks such as radon gas and noise exposure which may cause health problems.