Filtering surgery has been found to be less successful in certain types of glaucoma. These include young patients, those with pigmentary glaucoma, secondary glaucoma, angle recession glaucoma, aphakic or pseudophakic glaucoma, and patients requiring reoperation. This study describes the authors' attempt to evaluate the effectiveness of conventional trabeculectomy with intraoperative application of mitomycin C in such patients. Ten eyes of 8 patients were evaluated in this study. Of these cases 4 eyes (2 bilateral cases) were from the primary juvenile open angle group; 2 eyes each had pseudophakic glaucoma and previous anti-glaucoma surgery which had failed; one eye had aphakic glaucoma and the last suffered from angle recession glaucoma. The intraocular pressure was successfully controlled in all the ten eyes. The preoperative IOP ranged from 28 to 50 mm Hg and the postoperative IOP ranged from 7 to 16 mm Hg. The postoperative complications were minimal.