Long COVID presents with a variety of symptoms, some of which could be related to autonomic dysfunction. Our aim was to evaluate the prevalence of autonomic dysfunction in long COVID patients.We conducted a cross-sectional study and included all consecutive patients enrolled in several clinical research studies. We performed the following autonomic dysfunction markers: heart rate variability, heart rate, systolic and diastolic blood pressure changes during NASA Lean Test, cardiopulmonary exercise testing and a Composite-Autonomic-Symptom-Score (COMPASS)-31 scale. We used linear regression to calculate the contribution of each dysautonomia measure on symptom burden as measured by the modified COVID-19 Yorkshire scale.We included 100 patients for this study. Our sample population had a mean age of 56+/-11 years, included 53% minorities, and 32% were women. Dysautonomia, as defined by an abnormal COMPASS-31, was seen in 82% (95% confidence interval [CI] 72-89) of our study population, while cardiovascular resting dysautonomia, as represented by an abnormal heart rate variability, was seen in 60% (95% CI 48-70) of our study population. Orthostatic hypotension was observed in 12% of our study population, and postural orthostatic tachycardia syndrome (POTS) was found in 10% of our study population. In our adjusted analysis, we found that the beta coefficient for the COMPASS-31 score (0.37) was significant on changes in a self-reported long COVID symptom burden. The orthostatic intolerance and gastrointestinal domains of the COMPASS-31 were associated with the highest long COVID symptom burden.Dysautonomia is common in long COVID patients and contributes to the overall symptoms seen in long COVID. Identifying dysautonomia has important diagnostic and therapeutic implications. Background: Methods: Results: Conclusion: