Advanced glaucoma in 140 eyes of 136 patients was treated with contact transscleral continuous wave neodymium:YAG (Nd:YAG) laser cyclophotocoagulation (CYC) with a sapphire-tipped probe. The anterior edge of the probe was placed 0.5 to 1.5 mm posterior to the limbus, using 7 to 9 W of power for 0.7 seconds with 32 to 40 applications, sparing the 3 and 9 o'clock meridians. Patients were studied prospectively. The mean preoperative intraocular pressure (IOP) of 36.7 +/- 0.97 mmHg decreased to 21.2 +/- 0.99 mmHg (P = 0.004) after treatment (mean follow-up, 3.2 +/- 0.35 months) for a mean decrease in IOP of 15.5 +/- 1.21 mmHg and a mean percent decrease of 39%. Forty-one eyes were followed 6 or more months (mean, 6.7 +/- 0.25 months). The CYC reduced IOP to 25 mmHg or less in 71% of eyes, to 22 mmHg or less in 62% of eyes, and to 19 mmHg or less in 49% of eyes. Maximum lowering of IOP occurred 1 week to 1 month after treatment and remained at that level through 6 months of follow-up. Retreatment was required in 11% of patients; only one patient was retreated more than once. Four patients treated with 9 W of power developed IOPs below 5 mmHg; two of these patients had an IOP of 0 mmHg. Other complications of therapy were minimal, and patients had little pain. There was no significant change in visual acuity. Early results of this newly available therapy are encouraging.