This research looks specifically at the perceived needs of secondary school science teachers in Malaysia so that subsequent effective in-service programmes can be planned and implemented. The prime aim of this cross-sectional survey study is to ascertain the perceived needs of 1,690 practicing secondary school science teachers, characterized by gender, school location, and area of specialization. The main instrument used is a questionnaire. The validity and reliability of the instrument were systematically established through relevant test procedures. The questionnaire seeks feedback on the eight dimensions of science teachers' needs: generic pedagogical knowledge and skills, knowledge and skills in Science subjects, managing and delivering science instruction, diagnosing and evaluating students, planning science instruction, administering science instructional facilities and equipment, integration of multimedia technology and the use of English language in science instruction. Data were descriptively analyzed, followed by a series of chi square analysis. Results of the descriptive analysis demonstrate that the most prevalent needs of the Malaysian secondary school science teachers are the integration of multimedia and the use of English in science instruction. When measures of association were gauged between the science teachers' needs and the independent variables, it was found that significant associations exist. The associations were apparent between most of the dimensions of science teachers' needs and school location.