The current study aimed to determine the requirements of Trends of International Mathematics and Science Study (TIMSS 2019) and to find out the extent to which the content of science textbooks for grades (5–8) in the Sultanate of Oman includes the requirements of TIMSS 2019. Only the content dimension has been taken into account when conducting the content analysis. The study population includes all science books from the fifth to the eighth grade for the academic year 2021–2022. The study identified and organized the requirements in the study tool, and after confirming its validity and reliability, the analysis was performed, and data were collected and analyzed statistically using frequencies and percentages. The results showed a general lack of inclusion of TIMSS 2019 requirements in all grades (5–8), with (14.15%) of TIMSS 2019 requirements included in the fifth grade, (27.36%) in the sixth grade, (56.60%) in the seventh grade, and (36.79%) in the eighth grade. When studying the cumulative inclusion of TIMSS 2019 standards in classes (5–8) it was found that there was a similarity in the ratio in biology, a 4.5% difference in chemistry, a 13.5% difference in physics, and a 9.5% difference in Earth sciences. The study recommends reconsidering the content of science books for grades (5–8) in the Sultanate of Oman and including the missing requirements of TIMSS 2019 in the content of science books for these grades and benefiting from the tool that was prepared to apply it to current and future science books.