this study aimed to investigate the knowledge, attitudes and practices of Omani science teachers towards sustainable development issues (climate changes, energy sources & biodiversity) and their relation to gender. The study population was all science teachers on the provinces of North Batinah and North Sharqiah for the year (2011/ 2012), while the study sample consisted of ale and female teachers. For the purposes of the study, and answering its questions, the researcher constructed three instruments: a knowledge test consisting of (27) items, attitudes scale consisting of (30) items, and practices' scale consisting of (12) items. The validity of the instruments was verified by a panel of (11) judges, while their reliabilities were calculated using Cronbach-Alpha coefficient of internal consistency. It was found to be (0.82) for the test, (0.95) for the attitudes scale, and (0.83) for the practices scale which indicates suitability of the three instruments for the study purposes. The results of the study revealed low level of science teachers' knowledge of sustainable development issues (M% = 52.74), positive attitudes towards them (M. = 4.17), and good practices concerning these issues (M = 2.85). Results revealed also there were significant differences (a = 0.05) in teachers' Knowledge and attitudes with respect to gender in favor of female teachers, while there was no significant difference (a = 0.05) in teachers' practices with respect to gender. Accordingly, the researcher suggests further studies and recommends enhancing teachers' knowledge of sustainable development issues.