The current study explores the differences in metacognitive awareness perceptions of students who had high and low scores on TIMSS-like science tests. The sample consisted of 937 Omani students, 478 in Grade Five and 459 in Grade Nine. TIMSS-like tests were specially designed for both grade levels, and students also completed a metacognitive awareness perceptions inventory which explored their use of four main skills: planning, information management strategies, debugging strategies and evaluation. MANOVA was used to analyze the data. The findings indicated that students with high scores in the TIMSS-like test out-performed students with low scores in the test on all four metacognitive skills surveyed. This was true for all three performance areas analysed: performance in the TIMSS-like test as a whole, performance in lower-level test questions and performance in higher-level test questions. These findings highlight the extent to which students’ metacognitive skills influence their performance in science tests. The study recommends that students be trained to improve their metacognitive skills, reviews several methods for doing this, and suggests that such training might better prepare them for taking science tests. However, it also notes that further research is needed to explore the impact of metacognitive training on student performance in specific science examinations such as TIMSS.