Introduction/Aim. Argon Laser Trabeculoplasty (ALT) is a recognized method for reducing intraocular pressure (IOP) in patients with open angle glaucoma. The aim of this study was to compare the effects of primary medicament therapy and primary ALT on IOP regulation and stability of perimetry findings. Methods. A total of 50 eyes of 35 patients were treated with primary ALT while 50 eyes of 36 patients were treated with primary medicament therapy with 0.5% timolol with 20, 0.005% latanoprost 18 and with 2% dorzolamid 12 eyes. IOP was controled at 3 months, and the visual field at 6 months during a 30-month follow-up period. Results. In the first 24 months of follow-up there was no statistically significant difference in percentage of eyes with successfully regulated IOP. At 27th and 30th month, in the group primarily treated with medicaments a statistically significant higher percentage of successfully regulated IOP was observed in 98%, and 96% of the eyes, respectively, while in the group primarily treated with ALT the decline in the percentage of successfully regulated IOP was observed in 78% and 76% of the eyes, (χ2-test, p = 0.002, p = 0.140). Both therapy groups showed stability of perimetry findings without statistically significant difference in the values of mean deviation (MD) index until the end of the monitoring period. The dynamics of change in MD index value showed a statistically significant greater decline in this parameter in subjects who had been primarily treated with medications during the last six months of follow-up, (two-factor analysis of variance with a repeated measurement, factor of time × type of therapy, p = 0.030). Conclusion. Primary ALT equally successfully regulates IOP and restores stability of perimetry findings in patients with open angle glaucoma like the primary medicament therapy.