To evaluate the clinical results combined phacoemulsification and deep sclerectomy (PDS) with the use of mitomicin C (MMC) at different sites. PDS with MMC was performed in patients with open angle glaucoma and cataract. The patients were divided into two groups. In 16 eyes of the first group, MMC (0.2 mg/ml) was applied to subconjunctival area and under the superficial scleral flap. In 16 eyes of the second group, MMC was applied only to the place under the superficial scleral flap. It was compared the effects of different MMC applications in between the groups. Preoperative mean intraocular pressure (IOP) was significantly decreased from 25.84±3.78 mmHg to 16.34±3.33 mmHg (p<0.001). Preoperative best corrected visual acuity (BCVA) was improved from 0.2 to 0.7. Complete final success rates were 67.3% in the first group and 54.2% in the second group. The most common MMC dependent complication was avascular bleb formation which was seen in 5 eyes (31.25%) of the first group and 2 eyes (12.5%) of the second group. Cystic bleb formation was seen in one eye of the second group. The differences in both success rates and complications were statistically significant (p<0.05). MMC is more effective when it is applied to the subconjunctival area together with the place under the superficial scleral flap. However this procedure increases the rate of complications such as avasculer bleb formation.