This is a case‐control study on the relationship between strength of the hamstrings and quadriceps muscle and running injuries. Sixteen male runners, who had sustained a medically treated running injury during the year prior to this study, were matched for weekly running distance and age with 16 male noninjured control runners. All subjects were fit at the time of measurement. Hamstring (H) and quadriceps (Q) strength torque was measured isometrically at knee angles of 45°and 60°, respectively. The absolute torque value was used to analyze the difference in strength between muscles in injured subjects. The torque value relative to body weight was used to analyze the difference between injured and noninjured runners. Also the H/Q ratio was calculated. In injured subjects all measurements showed no significant (p>0.05) difference between the injured and noninjured side of the body. A previously injured runner showed a trend to have a higher isometric H and Q torque value relative to body weight in comparison with a noninjured control runner. This trend even proved significant when the mean isometric quadriceps torque of the left leg (p<0.05) and the right leg (p<0.01) of a noninjured runner was compared with the mean isometric quadriceps torque of the injured leg of a runner. No such trend was found with regard to the H/Q ratio. These findings do not support the hypothesis that muscle strength imbalance will lead to a running injury, nor do they support the hypothesis that due to the mechanics of running the H tends to strengthen relatively more than the Q muscle. Also the hypothesis that an injured runner tends to have weaker H and Q muscles than noninjured runners was not confirmed. However, both the retrospective and the case‐control approach to the problem has its limitations. The“true”relationship between muscular imbalance or muscular weakness and running injury can only be clarified by a prospective study in which at baseline all possible internal and external risk factors for running injury are registered carefully.