This study aimed at identifying the levels of scientific reasoning of upper primary stage (grades 4-7) science teachers based on their use of a problem-solving strategy. The study sample (N = 138; 32 % male and 68 % female) was randomly selected using stratified sampling from an original population of 437 upper primary school teachers. The scientific reasoning test was based on a problem-solving strategy and consisted of five parts (32 items) covering basic problem-solving skills. Descriptive and inferential statistics were used to interpret the data. Results indicated that the level of scientific reasoning of these science teachers was high with significant gender differences (p = 0.05) on levels of scientific reasoning that favored the female teachers. The results also showed no significant differences (p > 0.05) in scientific thinking among teachers with different experiences, qualifications, and specializations. These results support holding professional development courses for teachers to develop their scientific reasoning and thinking skills.