Paclitaxel is a promising anti-cancer drug as well as a radiosensitizer for chemotherapy and radiotherapy applications. Because of the poor solubility of paclitaxel in water and most pharmaceutical reagents, it is usually formulated with an adjuvant called Cremophor(R) EL, which causes severe side effects. This work develops new dosage forms of paclitaxel for controlled release application, which do not require the adjuvant and, thus, can avoid its associated side effects. Paclitaxel was encapsulated into the PLGA matrix with various additives such as polyethylene glycol (PEG), isopropyl myristate (IPM) and d-alpha tocopheryl polyethylene glycol (Vitamin E TPGS). These additives were used to enhance the release rate of paclitaxel from the polymer matrix. Spray-drying and an hydraulic press were used to prepare paclitaxel-PLGA microspheres and discs. The microspheres and discs were given different irradiation doses to investigate their effects on the surface morphology (characterized by SEM, AFM and XPS) and in vitro release properties. There seems to be a small effect of the ionizing radiation on various formulations. Although the irradiation did not cause observable changes on the morphology of the polymer matrix, the release rate can be enhanced by a few per cent. It was found that PEG has the highest enhancement effect for release rate among all the additives investigated in this study.