Background: Long-term glaucoma medication has been suspected to be a risk factor for bleb failure following trabeculectomy. It was the goal of our study to investigate whether additive preoperative treatment with latanoprost has an effect on the outcome of subsequent trabeculectomy. Methods: We retrospectively analysed the outcome of trabeculectomy in 32 eyes of 16 patients who had received bilateral trabeculectomy within the Mainz-II study. This study had been designed to examine the effect of 6 months’ use of topical latanoprost therapy on iris darkening. The first eye of each patient was operated upon without preoperative latanoprost therapy; the other eye was operated on after 6 months’ treatment with latanoprost in addition to existing medical glaucoma treatment. We analysed the outcome of these patients and compared success rates and average intra-ocular pressures (IOPs) between the latanoprost treated and the untreated partner eyes. Success was defined as an average postoperative IOP of 18 mmHg or less. Results: We obtained IOP values from 13 of 16 patients, with a mean follow-up period of 6.8 years. Three patients were lost to follow-up. In both groups eight eyes (61.5%) had an average postoperative IOP (average of all IOPs measured in the follow-up period) of 18 mmHg or less. The mean average postoperative IOPs in the control group and in the latanoprost group were 15.2 mmHg and 15.8 mmHg, respectively. Intraindividual comparison revealed that one pair of eyes had equal IOPs, while six eyes in each group showed better postoperative IOP control than the respective partner eye. However, mean delta IOPs (maximum preoperative IOP minus average postoperative IOP) were 17.8 mmHg and 14.2 mmHg for the control group and latanoprost group, respectively. Conclusion: In this small group 6 months of additive preoperative treatment with latanoprost did not have a statistically significant effect on the success rate of trabeculectomy or on the postoperative IOP level following trabeculectomy. However, trabeculectomy in eyes preoperatively receiving latanoprost for 6 months might lead to a slightly smaller delta IOP than in eyes naive to prostaglandins. Background: Long-term glaucoma has been the principle of our study to investigate the additive preoperative treatment with latanoprost has an effect on the outcome of subsequent trabeculectomy. Methods: We retrospectively analyzed the outcome of trabeculectomy in 32 eyes of 16 patients who had received bilateral trabeculectomy within the Mainz-II study. This study had been designed to examine the effect of 6 months’ use of topical latanoprost therapy on iris darkening. The first eye of each the patient was operated upon without preoperative latanoprost therapy; the other eye was operated on after 6 months’ treatment with latanoprost in addition to existing medical glaucoma treatment. We analyzed the outcome of these patients and more success rates and average intra-ocular pressures (IOPs) between the latanoprost treated and the untreated partner eyes. Success was defined as an average postoperativ Results: We obtained IOP values ​​from 13 of 16 patients, with a mean follow-up period of 6.8 years. Three patients were lost to follow-up. In both groups eight eyes (61.5%) had an average postoperative IOP (average of all IOPs measured in the follow-up period) of 18 mmHg or less. The mean average postoperative IOPs in the control group and in the latanoprost group were 15.2 mmHg and 15.8 mmHg, respectively. Intraindividual comparison revealed that One pair of eyes had equal IOPs, while six eyes in each group showed better postoperative IOP control than the respective partner eyes. However, the mean delta IOPs (maximum preoperative IOP minus average postoperative IOP) were 17.8 mmHg and 14.2 mmHg for the control group and latanoprost group, respectively. Conclusion: In this small group 6 months of additive preoperative treatment with latanoprost did not have a significant significant on the success rate of trabeculectomy or on the postoperative IOP level folHowever, trabeculectomy in eyes preoperatively receiving latanoprost for 6 months might lead to a slightly smaller delta IOP than in eyes naive to prostaglandins.