Abstract: A system for filling containers with a prescribed medication includes a support head for receiving a disposable syringe which allows the syringe to be pumped to transfer liquid to an from the syringe. A robot arm is also provided to carry medication and diluent containers to the syringe for withdrawing diluent to the syringe and injecting it into the medication container for mixing. In order to ensure alignment of the containers with the syringe, there is provided on the support head an additional needle grasping system which grasps and locates the needle for penetration of the membrane of the container. The support head includes a weigh scale as an integral element thereof so that the syringe is weighed after each step of the process.