Many recent studies in the field of mathematics and science education have been studying the effect of non-cognitive factors in students' achievement such as emotions, attitudes, values, beliefs, motivation, anxiety and grit. For example, attitude has been an important area in science education, and there have been many attempts to measure students attitudes to understand why they prefer a specific science subject (Reid; 2006). Zimmerman and Brogan (2015) stated that "grit predicts successful performance in a variety of contexts and found to be positively correlated with undergraduate grade average." Unfortunately, there are very few attempts if any have been studying the effect of grit on students' academic achievement in Bahrain. Bahrain is an important economic sector in the Arabic Gulf region; it has very ambitious and competitive developing economical and educational vision. This study aims to find relationships between students' level of grit and attitudes toward mathematics and science and the academic achievements in Bahrain secondary schools. "Grit questionnaire" was adapted from Duckworth et al. (2007), and was administered to a total of 646 secondary school students. "Attitudes toward mathematics" questionnaire was adapted from TIMSS (2011), and administered to a total of 349 secondary school students. "Attitudes toward science" questionnaire was adapted from TIMSS (2011), and administered to a total of 297 secondary school students. The results showed that grit is positively and significantly correlated to academic achievement in math only, while attitudes towards math and science was positively and significantly correlated to academic achievement in both subjects.