Platinum-based anticancer agents have been widely used in the clinic to successfully treat many different types of cancer. However, the therapeutic efficacy of platinum drugs is limited by serious side effects and the occurrence of inherent or acquired resistance of tumor cells. Nanoparticulate drug-delivery systems have the potential to reduce side effects and circumvent drug resistance. Among these, cisplatin nanocapsules represent a unique lipid formulation of cisplatin with an unsurpassed encapsulation efficiency, which dramatically increases the cytotoxicity of cisplatin in several cell lines in vitro. The mechanism responsible for the strongly enhanced cytotoxicity of the nanocapsules and the remarkable cell-line dependence will be reviewed. The requirements and possibilities for future successful therapeutic use of nanocapsules will be discussed, based on the mechanisms of cellular uptake of cisplatin nanocapsules and the first in vivo tests in a mouse model.