Primary Sjögren syndrome is one of the most prevalent autoimmune diseases that present with dry eye and dry mouth. But there is no proven effective treatment for Sjögren syndrome patient. The relation between toll-like receptor (TLR) and the pathogenesis of Sjögren syndrome has been reported. Hydroxychloroquine is TLR7 and TLR9 antagonist. A few studies have been reported the effectiveness of Hydroxychloroquine for Sjögren syndrome but no randomized controlled study has been done. So the investigators evaluate the effectiveness and safeness of Hydroxychloroquine for primary Sjögren syndrome by randomized controlled study (Hydroxychloroquine 300 mg once daily p.o. group (N = 30) versus placebo group (N = 30).

Inclusion Criteria:

• Patient who is diagnosed with primary Sjögren syndrome according to American/European consensus group (AECG) criteria
• Patient with the ability to give informed, dated and signed consent before the beginning of any proceedings related to the trial

Exclusion Criteria:

• Previous treated by Hydroxychloroquine but enough washout time after discontinuance of treatment, patient can be enrolled. (2 wks)
• Known cardiac disease, Respiratory disease, Renal disease, Gastrointestinal disease (except GERD)
• Diabetes mellitus
• Psoriasis
• Known drug allergy or hypersensitivity
• Previous or ongoing treatment by any drugs (include topical drug) which have effect on lacrimal system. But enough washout time after discontinuance of treatment, patient can be enrolled. (cf. SSRI, Anti-histamine, Pilocarpine, etc.)
• Angle closer glaucoma
• Patient who underwent previous intraocular surgery
• Macular disease
• Previous or ongoing treatment by drug which could have effect on macula
• Pregnancy
• Planning to get pregnant