Abstract: A disposable Luer lock syringe is provided with an integral Luer tapered needle connector and an integral, internally threaded, Luer lock retaining collar surrounding the connector and having a plurality of circumferentially spaced, longitudinal grooves. The grooved collar is circumferentially continuous and has sufficient rigidity for obtaining a desired fluid-tight connection with the hub of a needle assembly, while the grooves provide the collar with sufficient flexibility to permit the fracturing of the connector after the syringe is used so as to prevent reuse of the syringe.