ABSTRACT.Purpose: 3Tamoxifen and toremifene are non-steroidal anti-oestrogens widely used in the treatment of advanced breast cancer and as adjuvant therapy following surgery in early stage disease. Tamoxifene has also been approved for use in reducing the incidence of breast cancer amongst high risk women. However, certain well documented adverse effects, mainly involving the reproductive organs, have been reported amongst users of both drugs. The aim of this study was to monitor the ocular side-effects of both of these commonly used anti-oestrogens. Methods: Sixty postmenopausal (age range 50-79 years) breast cancer patients were randomized into adjuvant tamoxifen or toremifene therapy groups for 3 years. Prior to commencement of medication, a thorough ocular examination was undertaken. The first follow-up visit took place after 6 months and the remaining three at 12-month intervals thereafter. Results: Sixteen patients had cataract at the first visit (seven in the tamoxifen group and nine in the toremifene group). Ten patients developed cataract during the study period (five in each group), giving annual cataract rates of 6.8% and 6.2% in the tamoxifen and toremifene groups, respectively. Three patients had macular crystals at the first visit (one in the tamoxifen group and two in the toremifene group). The crystals remained stable throughout the follow-up. Macular drusen were diagnosed in five patients at the first ophthalmological check-up (two in the tamoxifen and three in the toremifene group). Two patients in the toremifene group developed drusen maculopathy during follow-up visits. Yellowish spots in the macular area were found in one tamoxifen-treated patient at the second visit. At the final visit after 3.5 years' follow-up the spots had disappeared. No abnormal corneal findings or keratopathy were documented during the follow-up. Conclusion: We observed no serious ocular side-effects among the 60 breast cancer patients treated with tamoxifen or toremifene over a 3.5-year period.