The purposes of this study were (1) to develop a science and technology (ST) ethics education program for prospective science teachers, (2) to examine the effect of the program on the perceptions of the participants, in terms of their ethics and education concerns, and (3) to evaluate the impact of the program design. The program utilized problem-based learning (PBL) which was performed as an iterative process during two cycles. A total of 23 and 29 prospective teachers in each cycle performed team activities. A PBL-based ST ethics education program for the science classroom setting was effective in enhancing participants' perceptions of ethics and education in ST. These perceptions motivated prospective science teachers to develop and implement ST ethics education in their future classrooms. The change in the prospective teachers' perceptions of ethical issues and the need for ethics education was greater when the topic was controversial.