Objective To improve the retrograde rotative-type interlocking intramedullary nail based on humeral bone dissection and cl inical appl ication, and investigate the cl inical values of modified retrograde rotative-type interlocking intramedullary nail for humeral shaft fracture. Methods Between March 2006 and March 2010, 146 patients with humeral shaft fractures were treated and fractures were fixed with the modified retrograde rotative-type interlocking intramedullary nail (the modified group, n=73) and with the retrograde rotative-type interlocking intramedullary nail (the original group, n=73). In the original group, there were 40 males and 33 females with an average age of 41 years; 41 cases were classified as transversefracture, 18 as obl ique fracture, 8 as spiral fracure, and 6 as comminuted fracture; the median disease duration was 11 days (range, 3 hours to 2 months); and close reduction fixation was performed in 27 cases and open reduction fixation in 46 cases. In the modified group, there were 39 males and 34 females with an average age of 40 years; 43 cases were classified as transverse fracture, 16 as obl ique fracture, 10 as spiral fracure, and 4 as comminuted fracture; the median disease duration was 13 days (range, 3 hours to 3 months); and close reduction fixation was performed in 31 cases and open reduction fixation in 42 cases. There was no significant difference in sex, age, fracture type, and disease duration between 2 groups (P gt; 0.05). The fracture heal ing and functional recovery of affected l imbs were compared between 2 groups after operation. Results The operation time and intraoperative blood loss in the modified group were significantly less than those in the original group (P lt; 0.05). Iatrogenic fracture occurred in 3 cases of the original group, which were cleavage fracture of supracondylar. No iatrogenic fracture occurred in the modified group. All incisions of 2 groups healed by first intention without compl ications of postoperative infections, metal fracture, and loosening of internal fixation, etc. A total of 116 patients were followed up more than 12 months in 2 groups with 58 patients in each group. The fracture heal ing time was (15 ± 3) weeks (fresh fracture) and (30 ± 12) weeks (old fracture and nonunion) in the modified group, and was (16 ± 4) weeks (fresh fracture) and (35 ± 14) weeks (old fracture) in the original group, showing significant differences between 2 groups (P lt; 0.05). The results of Neer shoulder score were excellent in 65 cases and good in 8 cases, and the results of Aitken and Rorabeck elbow function score were excellent in 61 cases and good in 12 casesin the original group; the results of Neer shoulder score were excellent in 67 cases and good in 6 cases, and the results of Aitken and Rorabeck elbow function score were excellent in 63 cases and good in 10 cases; and the excellent and good rates were 100% in 2 groups. Conclusion The modified retrograde rotative-type interlocking intramedullary nail has the advantages of easy operation and less compl ication, which is an effective and rel iable internal fixator.