This study was conducted to investigate the influence of addition of cetyl trimethyl ammo­nium bromide (CTAB), and amine [ethylamine (EA) or ethylene diamine (EDA)] to aqueous sodium hydroxide (NaOH) solution on polyester alkaline hydrolysis, The experimental vari­ables such as CTAB concentration, EA or EDA concentration, NaOH concentration, tempera­ture and time were compared, and the changes in physical and chemical properties of alkaline­hydrolyzed PET fabrics depending on their treated conditions were measured, The results are as follows: 1. By adding CTAB and amine in aqueous NaOH solution, increasing effect on weight loss of PET fabrics was obtained in simultaneous addition of CTAB and EDA, but not in CTAB and EA. 2. By adding CTAB & EDA simultaneously, increasing effect on weight loss was obtained regardless of EDA concentration, time and temperature, and it was more effective at lower NaOH concentration. :l. The increase of void space (or irregularly grooved surface), of softness, of wickability, of dyeability on PET fabric, and the decrease of tensile strength, of molecular weight were observed according to the weight loss on the PET fabrics. These changes were equal to all alkaline-hydrolyzed PET fabrics regardless of addition of CTAB and amine. l. There was little changes on crystallinity, thermal behavior when PET fiber was treated with ,aqueous NaOH solution with CTAB and EDA. These results supported that increasing effect on weight loss take place without inducing of fine structural change of PET fibers.