['Studies that investigated possible associations between the complexity of proximal humeral fractures and patient characteristics are rare. We hypothesized that the grade of fracture complexity may correlate with age and gender of hospitalized, adult patients.', 'Based on the Neer classification, we defined four radiological grades of fracture complexity. The data of adult patients that were treated during a 9-year period at a German hospital serving a town of 80,000 inhabitants was reviewed.', 'Seven hundred and eighty fractures were evaluated [518 female/262 male (66.41/33.59\xa0%), average age 64.2\xa0years (range 17.4-99.2)]. During the study period, the number of fractures increased to 167\xa0%. Almost two-thirds of the patients were females and older than 60\xa0years. Of all fractures, 86\xa0% were displaced fractures. In patients younger than 60\xa0years, 1.99-fold more complex fractures occurred in males (32.4\xa0%) than in females (16.2\xa0%). In contrast, in patients older than 60\xa0years, 1.72-fold more complex fractures occurred in females (54.1\xa0%) than in males (31.5\xa0%). There was a significant association between low-energy trauma and female gender older than 60\xa0years.'] Is the complexity of proximal humeral fractures age and gender specific?