This study aimed to identify misconceptions of 1st year and 4th year pre-service science teachers about the greenhouse effect. A questionnaire developed by Boyes and Stanisstreet ("Journal of Science Education and Technology," 2(4), 541-557, 1993) was administered to 163 pre-service science teachers in the College of Education at Kuwait University. The questionnaire consisted of 36 statements scored on a three-point Likert scale. The statements were arranged into three sections each containing 12 statements. Using means, frequency, percentage, and t test, the results indicated that most pre-service science teachers have some misconceptions about ozone layer, global warming, and issues related with causes, consequences of the greenhouse effect and the ways to alleviate its effect.