Objective To compare the effectiveness between locking compression plate (LCP) and locked intramedullary nail (IMN) for humeral shaft fractures of types B and C. Methods Between January 2010 and January 2012, 46 patients with humeral shaft fractures of types B and C were treated, and the clinical data were retrospectively analyzed. LCP was used for internal fixation in 22 cases (LCP group), and IMN in 24 cases (IMN group). There was no significant difference in gender, age, injury causes, the side of fracture, the site of fracture, the type of fracture, associated injury, and time from injury to operation between 2 groups (P gt; 0.05). The regular clinical examination and evaluation of radiography were done. Shoulder function was evaluated by Neer grading system and elbow function was evaluated by Mayo elbow performance score after operation. Results The operation time and intraoperative blood loss in IMN group were significantly lower than those in LCP group (P lt; 0.05). There was no significant difference in hospitalization time between 2 groups (t=0.344, P=0.733). All patients were followed up 16.8 months on average (range, 12-24 months). At 6 months after operation, bone nonunion occurred in 1 patient of LCP group and in 2 patients of IMN group; the bone healing rate was 95.5% (21/22) in LCP group and 91.7% (22/24) in IMN group, showing no significant difference (χ2=0.000, P=1.000). Except for nonunion patients, the bone healing time was (11.77 ± 0.75) weeks in LCP group and (11.38 ± 0.82) weeks in IMN group, showing no significant difference (t=1.705, P=0.095). Between LCP and IMN groups, significant differences were found in radial nerve injury (4 cases vs. 0 case) and impingement of shoulder (0 case vs. 6 cases) (P lt; 0.05), but no significant difference in superficial infection (1 case vs. 0 case) and iatrogenic fracture (1 case vs. 2 cases) (P gt; 0.05). There was no significant difference in shoulder function and elbow function at 1 year after operation between 2 groups (P gt; 0.05). Conclusion LCP fixation and IMN fixation for humeral shaft fractures of types B and C can achieved satisfactory results. More attention should be paid to avoiding radial nerve injury by fixation of LCP; nail tail should be buried deeply into the cortex of the greater tuberosity and rotator cuff should be protected to decrease the rate of impingement of shoulder by fixation of IMN.