Full Stage Lay Summary The current epidemiological evidence regarding the association between mobile phone use and brain cancer is largely reassuring, but several studies have reported an increased risk in the highest mobile phone users. What is more, most studies to date have included only adults, but the use of communication technologies is rising particularly among younger generations, who are exposed to radiofrequency electromagnetic fields from an early age. The MOBI-KIDS study, a multinational case-control study of mobile phone use and the risk of brain cancer in 10-24 year-olds, was launched to fill this gap. MOBI-KIDS is the largest childhood/adolescence brain cancer study to date including 2,200 cases and 4,400 controls from 15 countries. The study addresses a wide range of risk factors for brain cancer in this age group, thus providing an important evidence base for the primary prevention of this disease. This application seeks funding for the New Zealand arm of MOBI-KIDS.