Paroxysmal atrial fibrillation (PAF), which is in the sub-group of atrial fibrillation that spontaneously resolves within 48 hours and does not last more than 7 days, is one of the most important causes of cryptogenic stroke. Other than ECG findings, there are no biochemical diagnostic criteria for PAF. Early diagnosis of PAF reduces the risk of morbidity and mortality. Therefore, the determination of new diagnostic markers is of importance. Metabolomics methods have recently started to be used for this purpose. Carnitine profiling with LC-MS/MS is a fast, inexpensive metabolomics screening method with high sensitivity and has started to be used for the determination of new diagnostic markers. The aim of this study was to investigate the viability of the carnitine profile as a new biochemical marker supporting diagnosis in PAF patients. A total of 27 carnitine ester profiles were examined with the LC-MS/MS method using serum samples taken from 41 patients diagnosed with PAF from ECG findings and 42 healthy individuals with sinus rhythm. The C14, C16:1 and C18:1 serum carnitine ester levels of the PAF patients were determined to be statistically significantly higher than those of the healthy control group (p<0.05) and C6DC levels were found to be significantly lower (p<0.05). The results of the study strengthened the view that with measurements made with LC-MS/MS, the carnitine profile, which is an inexpensive, sensitive, reference method, can be used as an objective biochemical test to support diagnosis.