Research on ErbB receptors has spearheaded the rational cancer drug design, and ErbB1 (also known as EGFR) and ErbB2 are among the first clinically validated targeted therapies. Despite the fact that applicability of ErbB4 as a drug target is still uncertain, several patents involving utilization of ErbB4 have recently been issued. Manipulation of functions of ErbB4 may be therapeutically beneficial in cancer but also in psychiatric and cardiovascular disorders. In addition, analyzing expression or mutations of ErbB4 may provide prognostic or predictive value. Contents of ErbB4-related patents, as well as biology of ErbB4 and its alternatively spliced isoforms, will be reviewed in this article.