Trabeculotomy combined with sinusotomy was performed in 30 eyes with advanced open angle glaucoma, whose intraocular pressure (IOP) had been controlled in their high teens with only topical medications. The mean pre- and postoperative IOP levels were 18.2 +/- 1.2 mmHg (mean +/- standard deviation) and 13.2 +/- 1.2 mmHg and the pressure reduction was 4.6 +/- 2.4 mmHg. Average pressure reduction was 28.8 +/- 9.3% and pressure reduction of 30% or more was obtained in 45% of the treated eyes. The pre- and postoperative medication scores were 4.47 +/- 1.50 and 3.07 +/- 1.17, respectively. There was statistically significant difference between the pre- and postoperative medication score. We had no cases in which the IOP reduction was greater than 9 mmHg and postoperative IOP was 9 mmHg or less. A 3-line drop in visual acuity was seen in only one eye. Twenty two of 30 eyes (73%) were controlled at 14 mmHg or less with medications at the last examination. These results show that trabeculotomy combined with sinusotomy in effective, and this procedure can be considered as an alternative choice for surgical treatment in advanced glaucoma.