RT Journal Article SR Electronic T1 How to perform and interpret the sweat test JF Archives of disease in childhood - Education & practice edition JO Arch Dis Child Educ Pract Ed FD BMJ Publishing Group Ltd and Royal College of Paediatrics and Child Health SP edpract-2018-316615 DO 10.1136/archdischild-2018-316615 A1 Anthony Brown A1 Laura Jenkins A1 Alastair Reid A1 Anne Leavy A1 Glen McDowell A1 Claire McIlroy A1 Andrew Thompson A1 Ben McNaughten YR 2019 UL http://ep.bmj.com/content/early/2019/11/18/archdischild-2018-316615.abstract AB Cystic fibrosis (CF) is the most common life-threatening autosomal-recessive disease affecting Caucasians in the western world. The sweat test is the main diagnostic test for CF. It is indicated as part of the clinical assessment for infants that have picked up on the national neonatal screening programme. It may also be requested where clinical suspicion of a diagnosis of CF exists despite normal screening results. This article outlines the physiological basis behind sweat testing and the technical aspects of performing the test. Indications for performing the test are also considered. The article aims to provide clinicians with a guide to interpretation of results.