Abstract: The present invention relates to a delivery system useful for water-insoluble drugs, therapeutic agents, and diagnostic agents. More particularly, it relates to a method of packaging water-insoluble substances such as, for example, a drug or other therapeutic or diagnostic agent, to facilitate uptake into the human or animal body and to substances packaged by this method. The packaging method renders the water-insoluble substance water-soluble by packaging it in an amphiphilic polymer that is soluble in water. The invention also relates to a method of treating cancer through administering a water-insoluble drug or other therapeutic or diagnostic agent packaged according to the method describe above.