BACKGROUND/AIMS: To determine the prevalence of autonomic dysfunction among Korean patients with primary Sjogren\'s syndrome (pSS) and its associations with the clinical features of pSS. METHODS: We analyzed 154 participants from the Korean Initiative of primary Sjogren\'s Syndrome (KISS) as a prospective pSS cohort and 154 age- and sex-matched healthy controls. A standardized 5-minute, supine, resting heart rate variability (HRV) test was performed, and autonomic dysfunction was defined as standard deviation of normal-to-normal RR intervals (SDNN) < 30 ms in patients < 50 years old and SDNN < 20 ms in patients >/= 50 years old. The associations between autonomic dysfunction and various clinical features of pSS were analyzed. RESULTS: The overall autonomic activity in patients with pSS was significantly lower than that in controls. Autonomic dysfunction with the HRV test was observed in 35.7% of the KISS participants and was associated with a higher European League Against Rheumatism Sjogren\'s Syndrome Patient Reported Index fatigue score (p = 0.024). Raynaud\'s phenomenon was a more frequent clinical presentation in pSS patients with autonomic dysfunction than in those without autonomic dysfunction (29.4% and 14.4%, respectively; p = 0.048). Decreased parasympathetic activity was observed in 41.6% of pSS patients. No differences were found in the oral and ocular signs of pSS according to the decreased parasympathetic activity. CONCLUSIONS: In Korean patients with pSS, decreased and imbalanced autonomic activity is prevalent and is associated with fatigue. However, an association between autonomic dysfunction and glandular manifestations was not detected.