Purpose: To determine the efficacy of the dark-room prone provocative test (DRPT) for primary angle closure glaucoma. Method and subject: clinical trials study, 64 eyes of 41 subjects aged 35 years, whose peripheral anterior chamber were or or = 8 mmHg rise from baseline was considered as a positive test. Result: The mean IOP pre-test was 13.13 + or - 1.68 mmHg and post-test was 18.61 + or - .2.12 mmHg, showing a significant increase with p=0.001. The DRPT results were positive in 22 eyes (34.491), 42 eyes (65.6 percent) have negative result. There is no significant difference in gender and age between positive and negative group. The positive rate in the fellow eye of subjects who has beef! diagnosed with glaucoma in one eye was significantly higher than those who have no history of glaucoma, p=0.002. The mean IOP pre-test of positive group was significantly higher than that of negative group with p=0.028. The number of angle closure was also significantly higher in positive group with p=0.000. The number of angle closure was significantly correlated with the amount of IOP elevation induced by DRPT (r=0.827). Conclusion: DRPT is an effective test in the detection of primary angle closure glaucoma.