A transdermal delivery device includes a plurality of microneedles for injecting a substance such as a pharmaceutical agent into or below the stratum corneum of the skin. The device has housing formed from a top and bottom wall to define a chamber for containing a pharmaceutical agent. An inlet port is provided in the top wall of the housing for supplying the pharmaceutical agent to the chamber and directing the agent to the microneedles. The housing can have a Luer lock type fitting for coupling with a syringe having a Luer lock collar to inject the pharmaceutical agent into the housing. The housing can be divided into a plurality of chambers by an internal wall for supplying different agents simultaneously or sequentially to a patient. The microneedles have a length of about 5-250 microns and generally about 50-100 microns.