Department of Pharmacy, Annamalai University, Annamalainagar – Chidambaram (Tamil Nadu), INDIA Acetazolamide sustained release (S.R.) capsule 500 mg was prepared according to release pattern suggested by Wagner (1971). Comparative release pattern of the drug from S.R. pellets by using glyceryl monostearate, microcrystalline wax and microcrystalline wax and glyceryl distearate was studied. 00 hard gelatin capsule filled with combination of 35% of drug coated pellets (DC) and 65% of DC with 1:1 ratio of microcrystalline wax and glyceryl distearate on basis of drug content was successful and found stable in evaluations. Application of various kinetic equations to in vitro data indicated biphasic zero order release. Keywords : ACETAZOLAMIDE 500 MG, SUSTAINED RELEASE, CAPSULE, IN VITRO