Every year influenza disease affects about 10% of the world's population, i.e. some 500 million people. An international surveillance network organised by the WHO follows the circulation of influenza viruses both in man and animals and monitors the emergence of new strains. Each year WHO conducts two different global meetings, in February and September, to summarize surveillance data so that new recommendations can be proposed for vaccine composition for the influenza seasons in the northern and southern hemispheres, respectively. Vaccine manufacturers have to proceed with two different vaccine production campaigns to match the recommendations for the two hemispheres. Each new vaccine formulation must be validated, and tolerability and immunogenicity are tested in a clinical study before each new vaccine formulation is submitted for Market Authorisation. This requires a vaccine industry with a considerable degree of experience from working under very tight time limits. With two six-months production periods, at least 250 million doses are brought to the global market in more than 100 countries each year. In this presentation we will discuss all the major steps of this vaccine production process with its underlying difficulties, milestones and bottlenecks.