Most pediatricians eventually encounter a patient with a clinical presentation that warrants the consideration of a sweat test to rule out of confirm the diagnosis of cystic fibrosis. This article discusses, in a series of questions and answers, the currently available sweat testing methods and describes the various methods' reliability, limitations, and frequency of use. In addition, sweat testing utilization and the interpretation and evaluation of test results are discussed so that the clinician can critically analyze the laboratory data.