Objective To evaluate the changes of serum level of D-dimer in the elderly essential hypertensive patients with or without coexisting benign prostatic hyperplasia (BPH) and compare the results with those of the healthy elderly people and the patients with simple BPH in order to investigate the clinical significance of serum D-dimer in the elderly essential hypertensive patients with coexisting BPH and its relationship with mortality. Methods A total of 157 elderly patients with primary hypertension admitted in our hospital from January 2009 to December 2012 were recruited in this study. They were divided into 2 groups according to whether coexisting BPH, that is, simple hypertension group (group H, n＝80) and coexisting group (group C, n＝77). Another 50 healthy elderly men (group N) and 50 elderly patients of simple BPH (group P) hospitalized during the same period served as control groups respectively. The serum level of D-dimer were measured and compared in all the 4 groups. In the meanwhile, the number of death was calculated in the cohort during the 4 years’ follow-up and the relationship between the mortality and serum D-dimer was analyzed. Results The serum levels of D-dimer were higher in groups H and C than in group N, while, that in group C was the highest among all groups. During the 4 years’ follow-up, there were totally 16 patients died in the cohort, and all of them were from group H and group C, with more in group C than in group H. For all these died patients, their serum D-dimer was obviously higher than the patients from the same group. What’s more, the increase even became more severely in 1 to 3d before death. Conclusion The serum D-dimer is increased in the elderly essential hypertensive patients than in normal old men, and it is more higher in the elderly hypertensive patients with coexisting BPH. Its increase is closely related to mortality. Our results suggest that we pay attention to the serum D-dimer for the elderly hypertensive patients, especially with coexisting BPH, and focus on the protection of vascular endothelial function, thus to decrease the mortality and improve the quality of life.