Objective To evaluate the clinical characteristics of younger patients with primary angle-closure glaucoma (PACG). Methods Retrospective case control study. Twelve patients (22 eyes) aged 40 or younger with a confirmed diagnosis of PACG from January 2006 to July 2010 were investigated. At the time of the initial diagnosis, all patients were in the middle or late stageand did not feel significant pain. Eighteen eyes underwent surgical treatment. Full ophthalmic examinations were performed. They were compared to 217 older patients (236 eyes) with PACG who underwent trabeculectomy during the same period. The clinical characteristics, including clinical presentations,surgical results and complications were evaluated. Data were analyzed with a paired t test and a chi-square test. Results The mean age of the younger patients with PACG was (32.8±5.7)years.The majority of them were female (75％). The mean axial length was (21.1±1.9)mm. Plateau iris was the most common underlying etiology (91％), and only 1 case (2 eyes) was pupillary block. The mean follow-up period was (24.8±6.3)months. There was an (11.6±5.2)mmHg reduction in the final postoperative intraocular pressure (IOP) compared to preoperative IOP (t=6.456, P＜0.01). The main postoperative complications included shallow anterior chambers (44％) and malignant glaucoma (17％). The mean age of the older patients with PACG was (60.2±7.1)years. The majority of them were females (81％). The mean axial length was (21.5±2.7)mm. Pupillary block (81％) was the most common underlying etiology,and 19％ patients were Plateau iris. The differences of plateau iris and pupillary block were significant (x2=56.446, 14.303, P＜0.01). The incidence of postoperative shallow anterior chamber and postoperative malignant glaucoma was 10％ and 6％, respectively. There was a statistically significant difference in the incidence of postoperative shallow anterior chamber when younger patients were compared to older patients with PACG (x2=14.091, P＜0.01). Conclusion The younger PACG patients cannot b