OBJECTIVE To determine the effect on serum lipid levels of carteolol hydrochloride 1.0% or timolol maleate 0.5% given twice a day to women age 60 years and older with primary open-angle glaucoma or ocular hypertension. METHODS We included 112 patients in this double-masked, randomized, multicenter trial. Fasting clinical laboratory studies were evaluated at baseline and at 12 weeks. Patients were instructed not to change their dietary, alcohol consumption, or exercise habits during the study. RESULTS For the carteolol group, the high-density lipoprotein (HDL) and total cholesterol/high-density lipoprotein (TC/HDL) ratio at baseline of 50.1 +/- 1.5 mg/dl and 4.7 +/- 0.2 changed by the 12-week visit to 51.3 +/- 1.9 mg/dl (P = .25) and 4.6 +/- .02 (P = .47), respectively. For the timolol maleate group, the baseline HDL and TC/HDL ratio of 53.6 +/- 2.2 mg/dl and 4.4 +/- 0.2 changed to 50.2 +/- 1.9 mg/dl (P < .001) and 4.7 +/- 0.2 (P = .001), respectively, at the 12-week visit. Carteolol patients showed no significant change from baseline, whereas the HDL (P < .001) and TC/HDL ratio decreased (P = .001) significantly in the timolol maleate group. There also was a significant difference in the change from baseline at 12 weeks between carteolol and timolol maleate groups for the HDL and TC/HDL ratio (P = .01 and .012, respectively). No differences in TC, low-density lipoprotein (LDL), or triglycerides (TG) or in changes from baseline were observed between groups at 12 weeks (P > .05). At 12 weeks, no differences were observed between carteolol and timolol maleate groups in intraocular pressure or safety (P > .05), except that patients given carteolol demonstrated fewer solicited ocular symptoms (P = .007). CONCLUSIONS Carteolol appears to be neutral in its effect on serum lipid levels, whereas timolol maleate adversely affects the HDL and TC/HDL ratio in women age 60 years and older with ocular hypertension or primary open-angle glaucoma.