Abstract: The present invention is a safety syringe for use with a plurality of interchangeable needles. The plurality of needles may be inserted by the user into the safety syringe for use. In operations, the user selects the desired needle, e.g., a needle having a particular gauge or size or of a particular type. The user inserts the needle into a safety syringe comprising a barrel, a needle assembly area located within or attached to the barrel and a plunger. The needle couples to the syringe by a number of means. For instance, a locking mechanism may be used by which a needle hub located within the needle assembly has an area adapted to mate with a corresponding area on the needle. Or, the needle may be formed as part of a separate needle assembly, whereby the user will place the entire needle assembly onto the end of the syringe barrel. During use, the user operates the syringe, using one hand to depress the plunger, which ultimately causes a spring to propel the needle into the barrel of the syringe.