Fifty-three patients had MRI preoperatively. In our practice we do not have in our routine ordering MRI for diagnosis confirmation of distal biceps tendon ruptures. 30 of 32 (94%) complete tears had been confirmed by MRI (two patients had partial tear diagnosis by MRI and post-op diagnosis of complete tear). 19 of 21 patients (90%) with partial tears had been confirmed by MRI (two patients had complete tear diagnosis by MRI and post-op diagnosis of partial tear). Thus, sensivity and specificity for MRI were 94% and 90% respectively. 2 patients with wrong preoperative MRI description of complete tears had absent hook test and absent resisted hook tests respectively – confirming the post-op diagnosis. 2 patients with partial tears with misleading diagnosis by MRI of complete tears had painful hook test and painful resisted hook tests respectively – confirming the post-op diagnosis. In the contralateral arms, which served as the normal control group, 61 of 62 (98%) had a normal hook test. One patient had ABSENT hook test on his contralateral extremity because he had spontaneous rupture 5 years earlier which was treated non operatively. We developed Algorithm that can guide clinical to diagnosing primary distal biceps tendon tears. Unhookable ABSENT hook test indicates that there is no tendon in antecubital fossa behind examiner can hook his finger. In that situation examiner should perform resisted hook test. If there is ABSENT resisted hook test it indicates that it is complete distal biceps tendon rupture. Hookable hook test with no pain reproduced suggests that the distal biceps tendon is INTACT. ABNORMAL (Painful and hookable) hook test is indication of partial tears. However if examiner perform hook test that is unhookable and afterwards perform resisted hook test which is hookable that strongly indicates partial tear of distal biceps tendon.>