In 35 patients 37 trabeculectomies (TE) were performed using mitomycin as a fibrosisinhibitor. Mitomycin (0.5 mg/ml) was applied to the sclera (under the scleral flap) and conjunctiva in the area of the projected TE during 5 minutes using a small sponge. The indications for operation were: visual field progression in 15 eyes, too high IOP in 13 eyes and severe visual field defects (central island and/or centro coecal visual field defects) in 9 eyes. Six patients had Normal Pressure Glaucoma, 17 Primary Open Angle Glaucoma and 12 had other forms of glaucoma. There were 22 first TE's and 15 re-operations. The scleral flap was sutured with 5 to 8 10/0 nylon sutures. The system of a large number of sutures and subsequent suturelysis was our routine management for reducing complications after TE. This report deals with the postoperative period of the first three months. Suturelysis in combination with mitomycine caused an unexpected high number of postoperative hypotonies (IOP < = 6 mmHg with reduced visual acuity and/or retinal folds or large persistent choroidal detachment and shallow anterior chamber) In the 27 eyes who had suturelysis performed, 7 developed a hypotony. The hypotony may develop as late as three weeks postoperative after suturelysis!. Two eyes developed a hypotony without suturelysis. Seven patients needed resuturing of the scleral flap. The use of mitomycine to enhance filtration after TE may cause serious hypotonies if the scleral flap is not securely closed and if suturelysis is used too early or too extensively.