The first definition of the term was given in T 144/83 (OJ 1986, 301). According to this decision, therapy relates to the treatment of a disease in general or to a curative treatment in the narrow sense as well as the alleviation of the symptoms of pain and suffering.

It is established case law that a prophylactic treatment, aimed at maintaining health by preventing ill effects that would otherwise arise, amounts to a method for treatment by therapy as referred to in Art. 53(c) EPC, and that therapy is not limited to treatments which restore health by curing diseases which have already arisen (see e.g., G 5/83, OJ 1985, 64). Both prophylactic and curative methods of treating disease are covered by the word therapy, since both are directed to the maintenance or restoration of health (T 19/86, OJ 1989, 24; T 290/86, OJ 1992, 414; T 438/91, T 820/92, OJ 1995, 113).

In T 2420/13 the board stated that a "therapeutic treatment" required some intervention on the body or body part to be treated which caused a therapeutic effect.

The board in T 774/89 distinguished "therapy" from "performance improvement", finding that the purpose of therapy was invariably to restore the organism from a pathological to its original condition, or to prevent pathology in the first place, whereas a non-therapeutic improvement of performance took as its starting point a normal state (to be defined) (see T 385/09).

Therapeutic methods must also be distinguished from cosmetic methods. In G 1/07 (OJ 2011, 134) the Enlarged Board of Appeal pointed out that it was the express wording of Art. 53(c) EPC that only therapeutic methods were excluded from patentability (and thus cosmetic methods were not) and the exclusion could not be extended to treatments which were not therapeutic in character (see also T 1172/03 making reference to T 144/83, OJ 1986, 301).