We wish to thank Daniel Czarny, Rosa Dias Santilhiano, Andrei Saramovich, Fiona Savio, Georg Schäppi, Noortje Hamse, Brechje Gosens, Paul Angel and Alicia Stein‐Oakley for their assistance in translating studies published in languages other than English. The German Assistant (Microtac software) was used to translate papers published in German. David Hill kindly gave us access to the original data from his RCT of grass pollen immunotherapy in children with asthma. Betul Sin provided individual patient data from his RCT of immunotherapy with grass pollen and mite extracts. Jean Bousquet and Alicia Armentia provided methodological details of studies conducted by their groups. Steve Milan, Anna Bara and Karen Blackhall searched the Cochrane Airways Group database. David Badger and Vivienne Moore from the Australasian Cochrane Centre and Anna Bara provided helpful advice on the use of RevMan. Paul Montgomery read and approved the consumer synopsis.