In this study locus of control was find to correlate with problem solving ability of the in-service teachers. Further investigation by chi-square revealed significant difference between in-service teachers with external locus of control and mathematics problem solving ability. Locus of control which is the tendency to ascribe achievements and failures to either internal factors that they can control(effort, ability, motivation) or external factors that are beyond control (chance, luck, others’ actions) is an important factor that could affect the ways a teacher performs his teaching role. It could be ascertain that teachers who believe that effort and ability are essential in the learning of mathematics are likely to motivate and encourage their students to tackle and solve problems in mathematics whereas those who believe that luck, fate, chance or powerful others might not be favourably disposed towards encouraging their students in engaging in strenuous mathematics problem solving because they themselves attached their successes to luck, chance or fate.