Most research on duodenal ulcers has focused on bulbar ulcers; details on post-bulbar ulcers remain largely unknown. This study was conducted to determine the characteristics of patients with post-bulbar duodenal ulcers depending on their location. We conducted a retrospective study of hospitalized patients newly diagnosed with duodenal ulcers on endoscopy at a tertiary referral center in Japan between April 2004 and March 2019. Five hundred fifty-one patients diagnosed with duodenal ulcers were extracted for analysis. Ulcers were observed only in the bulbus in 383 cases, only in the post-bulbar duodenum in 82 cases, and were co-existing in both areas in 86 cases. The Bulbar group had less comorbidities and was more likely to have atrophic gastritis, while the Post-bulbar and Co-existing groups were more likely to be admitted for non-gastrointestinal conditions. Regular acid suppressant use was more common in the post-bulbar group than in the Bulbar group. Bulbar ulcers were associated with a shorter length of stay relative to post-bulbar and co-existing ulcers, but ulcer location was not an independent predictor of length of stay. Patients with co-existing bulbar and post-bulbar ulcers have characteristics similar to those with post-bulbar ulcers alone. Patients with post-bulbar ulcers and those with co-existing bulbar and post-bulbar ulcers have different characteristics and outcomes relative to patients with bulbar ulcers.