We retrospectively analyzed long-term effects of trabeculotomy combined with sinusotomy. We reviewed 29 eyes with primary open angle glaucoma and 6 eyes with psuedexfoliation glaucoma. The preoperative intraocular pressure was equal to or over 21 mmHg. All cases had been subjected to initial trabeculotomy combined with sinusotomy. The had been followed up for at least 3 years after surgery. The mean age was 57.8 years and the mean follow-up period was 40.5 months. The preoperative intraocular pressure was 24.3 +/- 5.9 mmHg (Mean +/- standard deviation) and the postoperative intraocular pressure was 15.8 +/- 3.8 mmHg. There was statistically significant difference between preoperative and postoperative intraocular pressure. The Kaplan-Meier life table method indicated a success rate at 50 months after surgery of 0.63 +/- 0.15, as defined by intraocular pressure of 20 mmHg or lower, and of 0.35 +/- 0.08 as defined by intraocular pressure equal to or lower than 14 mmHg. The success rate of filtering blebs was 0.10 +/- 0.05 at 50 months. Eleven of 35 eyes (37%) were controlled at equal to or below 14 mmHg and 20 of 35 (67%) eyes were controlled at equal to or lower than 16 mmHg at final postoperative intraocular pressure. The surgical results of trabeculotomy combined with sinusotomy remain effective in controlling intraocular pressure levels for long periods.