Background: A questionnaire was designed and administered to people living in Kocaeli province, Turkey, in order to determine their level of knowledge about smoking before the initiation of a social responsibility project aimed at increasing the smoking cessation rates in Kocaeli. Material-Method: The sample selection was made on the basis of the population sizes of 12 counties in Kocaeli province; participants over the age of 18 completed the questionnaire over the phone. Results: A total of 2721 participants were included in the study. It was found that the knowledge level about smoking-related diseases was quite high, and the conditions mentioned most frequently by the participants were lung diseases, cancer, and cardiac diseases. Only 2.8% of the subjects reported that they had no information about the harmful effects of smoking. Knowledge level was not different among age groups or educational levels of the participants.