Object In this paper, the authors aimed to summarize the clinical characteristics of ossification of the ligamentum flavum (OLF) associated with dural ossification (DO) and to identify improved methods for preoperative diagnosis. Methods Thirty-six patients who had undergone OLF surgery between February 2005 and September 2009 were included in this retrospective study. The patients were divided into 2 groups: one that included patients with intraoperative evidence of DO and a second group that included patients without DO. The clinical features of DO were summarized and the neurological status of the patients was evaluated pre- and postoperatively. Results The incidence rate of DO associated with OLF was 39% (14/36). The sensitivity and specificity of the tram track sign were found to be 93% and 59%, respectively. Dural ossification was found among 86% of the patients with tuberous type Sato classification. The postoperative neurological status of patients was generally improved relative to that observed prior to surgery, although neurological recovery did not differ between the 2 groups. Cerebrospinal fluid leakage was the main complication, occurring predominantly in the patients with DO, and all leaks resolved in all patients after comprehensive treatments. Conclusions The tram track sign and Sato classification were found to be useful for preoperative diagnosis of DO and for determining the surgical procedure to be performed. Dural ossification had no effect on postoperative neurological recovery.