Objective: Corneal refractive surgery has been gaining popularity among postmenopausal women over the past several years. Previous studies with different methods showed increased adrenergic activity in the postmenopausal period and suppressed sympathetic response with hormone replacement therapy. As pupil size may alter with sympathetic activity, we hypothesized that the success rate of corneal refractive surgery may be affected by hormone replacement therapy. The aim of this study was to evaluate the effects of hormone replacement therapy on pupil diameter. Material and Methods: Sixty-five healthy postmenopausal women who received hormone replacement therapy that was consisted of conjugated estrogen and medroxyprogesteron acetate have participated in this study. Pupil diameter was measured with an infrared pupillometer [OPD-Scan II Pupillometer/Corneal Wavefront Analyser ARK-10000 system (Nidek, Japan)] at the time of study enrollment and atleast 3 months (4.9 ±1.3) after the initiation of hormone replacement therapy. Results: Mean pupil diameters under mesopic/photopic conditions were 5.84±0.86mm/ 4.60±0.79mm before hormone replacement therapy and, 5.85±0.77mm/4.62±0.76 mm after hormone replacement therapy. The differences between 'before hormone replacement therapy' and 'after hormone replacement therapy' assessments were statistically insignificant (p=0,860 ve p=0,552 respectively). Conclusion: The effect of hormone replacement therapy on pupil size, either directly or via autonomic nervous system, was insignificant in postmenopausal women. However, it is recommended that the results of our study need to be confirmed by more detailed studies.