In Chile, Canada, Europe, Japan, and the USA, which are the main geographical areas for fish farming of high value fish such as salmonids, sea bass, sea bream, yellowtail and catfish, vaccination has been established as an important method for the prevention of infectious diseases. To make new vaccines available to the fish farming industry, pharmaceutical companies must comply with the regulatory framework for licensing of fish vaccines, which in recent years has become more regulated. Considerable scientific and regulatory skills are thus required to develop, document and license vaccines in accordance with the requirements in the different geographical areas. International co-operation to harmonise requirements for the licensing documentation is ongoing. Even though there are obvious benefits to the pharmaceutical industry from the harmonisation process, it may sometimes impose unreasonable requirements. The regulatory framework for fish vaccines clearly has an impact on the time for bringing a new fish vaccine to the market. Several hurdles need to be passed to complete the regulatory process, i.e. obtain a licence. Fulfilment of the rather detailed and extensive requirements for documentation of the production and controls, as well as safety and efficacy of the vaccine, represent a challenge to the pharmaceutical industry, as do the different national and regional licensing procedures. This paper describes regulatory constraints related to the documentation, the licensing process, the site of production and the continuing international harmonisation work, with emphasis on inactivated conventional fish vaccines.