Purpose: Glaucomatous neuropathy is a type of cell death by apoptosis. Apoptosis is a genetically controlled form of cell death, and one of its primary regulatory steps is the activation of the tumour suppressor protein p53, of which p21 is an effector protein. The association between p21 codon 31 polymorphism and primary open-angle glaucoma (POAG) patients was evaluated in this study. Methods: The study included 58 POAG patients and a control group of 59 healthy volunteers. Polymerase chain reaction-based analysis was used to resolve the p21 codon 31 polymorphism. Results: The genotype frequencies of p21 codon 31 polymorphism were statistically different (p <0.05) between the two groups. The Arg allele of the p21 codon 31 polymorphism was more frequently found in POAG patients than in healthy individuals (odds ratio: 2.389, 95% confidence interval: 1.14-5.01). Conclusion: This study suggests that an association exists between the Arg allele of the p21 codon 31 polymorphism and POAG in the Chinese population.