Primary frozen shoulder (PFS) is a common condition of uncertain etiology that is characterized by shoulder pain and restriction of active and passive glenohumeral motions. The pathophysiology involves chronic inflammation and fibrosis of the joint capsule. Single nucleotide polymorphisms (SNPs) at , , , and have been associated with risk of a variety of inflammatory diseases; however, no studies have examined these SNPs with susceptibility to PFS. We investigated allele and genotype frequencies of rs1143627 at , rs650108 at , rs1800469 at , and rs143383 at in 42 patients with PFS and 50 healthy controls in a Chinese Han population. Serum samples from both cohorts were evaluated to determine the expression levels of IL-1. We found that the rs1143627 CC genotype was associated with a decreased risk of PFS compared to the TT genotype ( = 0.022) and that serum IL-1 was expressed at a significantly higher level in the PFS cohort compared to that found in the control group ( < 0.001). Our findings indicated no evidence of an association between rs650108, rs1800469, or rs143383 and PFS. IL-1 is associated with susceptibility to PFS and may have a role in its pathogenesis in a Chinese Han population.