Parallel to the rapid increase in mobile phone use worldwide concerns have been raised about various health effects. Acute symptoms have by some individuals been reported to be triggered when holding the phone to the head during calls or being close to a base station for mobile telephony. Symptoms vary, but headache, fatigue and difficulties concentrating are among the most commonly reported. Exposure to radiofrequency fields have been proposed as the cause of the symptoms. Double blind provocation studies have however failed to provide support for such a causal link. In spite of this, some people are still convinced that their ill health is caused by exposure to radiofrequency fields from mobile phones. It has also been suggested that a greater number of people than those who report experiencing these reactions to radiofrequency fields might be affected without being aware of the triggering factor. In theory, long term effects after repeated frequent exposure to radiofrequency fields from mobile phones may exist regardless of whether acute effects exists or not. The first studies on a possible relation between mobile phone use and symptoms in the general population were cross-sectional studies. This study design gives little information on possible causal relationship and suffers from a risk of reverse causality as well as a nocebo effect. Lately however, a number of prospective cohort studies have been published. This presentation will provide an update of the knowledge on mobile phone use and the onset of symptoms from these studies.