Abstract: The effects of various percentages (0, 3, 6, 9, 12 and 15%) of Glycerol Mono Stearate (GMS), Stearic Acid (SA) and Cetyl Alcohol (CA) on the release rate of Ibuprofen (IB) from polyethylene glycol-4000 (PEG)-based suppositories were studied. Ibuprofen suppositories of PEG-4000 base were prepared using GMS, SA and CA separately in different formulations by fusion method. Dissolution studies showed a rapid release of the drug during 30-60 min from the PEG-based suppositories of IB and almost 75% of the drug was released within this period. But the incorporation of waxy additives GMS, CA and SA in the formulation reduces this rapid release rate of the drug. Three percent GMS containing PEG-based suppositories liberated about 70.0% of the drug within 6 h whereas maximum 45.0% and 51.0% of drug were liberated from 3% SA and 3% CA containing PEG-based suppositories, respectively, within the same time. The drug release reducing capabilities of the waxy additives were found to be in the following order SA>CA>GMS. Utilizing this capability of the additives, sustained release suppositories of ibuprofen could be formulated.