Kuwait, has participated in international TIMSS test for many years, however, there has been little systematic effort to compile and assess changes between genders. This study attempts to look at the results of Kuwaiti students on the TIMSS mathematics assessments in general and according to gender in particular and the views of supervisors on the relatively low performance of Kuwaiti students. The study employed a mixed method approach in which data analysis of test results, IEA-issued documents, and statistics and official reports were used. Two focus group interviews were conducted with a convenience sample of nine educational supervisors from mathematics and science. The results show that the performance of Kuwaiti students in both the fourth and eighth grades was extremely low on the TIMSS mathematics assessments in general and in content areas in particular, since the first participation in 1995, even though the performance of eighth graders showed a slight improvement in 2015 in all areas. The TIMSS results also show that the higher the level of thinking that was assessed, the lower the performance of Kuwaiti students was. The data indicate that throughout all years, Kuwaiti girls outperformed boys, considering the slight improvement especially in 2015, yet both performances lagged behind international norms. Focus group transcript analysis reveals that supervisors perceived that students' low performance on the TIMSS assessment test is related to a number of reasons as lack of interest in TIMSS test, unfamiliarity with TIMSS questions, and students' weakness in the Arabic language. The paper concludes the need to systematically evaluate the TIMSS results, and develop interventions and a competent national curriculum in Kuwait.