Human interferons are key cytokines secreted by the immune system. They exhibit antiviral, antitumor and immunomodulator activities. Interferons are degraded rather quickly in the organisms, especially when they are recognized as external substances. In order to make interferon therapies more effective, numerous delivery systems have been developed and widely studied in scientific papers and reviews. However, the aim of the present review is to study the available patents dealing with sustained interferon delivery. Delivery systems involving micro- and nanoparticles could be found abundantly among the inventions. Non-particulate delivery systems are represented principally by gels and liposomes. However, stents, domes and other types of matrices as well as conjugated interferons have also been patented. The polymers most frequently used for controlling release of interferon are poly(lactic-co-glycolic acid), polylactic acid and polyethylene glycol. Indirect methods constitute a challenging way to sustain interferon delivery by transferring protein encoding nucleic acids. Pegylated interferons are the leading commercial products, but encapsulated and genetically fused interferons are also close to enter the market. It is expected that nanoparticles and especially magnetic nanoparticles will have an important role in the future improvements.