Abstract: The application describes a method of introducing into a container a suspension or solution of a material in a propellant held under pressure, in particular a pharmaceutical material. The method comprises the steps of bringing a filling head into communication with the container; introducing a quantity of such suspension or solution into the container through the filling head; introducing a quantity of high pressure propellant without any of the said material into the filling head, thereby to flush through any suspension or solution remaining in the filling head; and withdrawing the filling head from the container. An apparatus and a filling head for carrying out the method are also described.