Purpose To investigate the effect of 3% diquafosol sodium ophthalmic solution (DQS) on aqueous tear volume increase in dry-eye patients with Sjögren's syndrome (SS). Methods In this pilot study, 17 dry-eye patients with SS (1 male and 16 females; mean age: 66.4 years) were enrolled and underwent topical instillation of two ophthalmic solutions, artificial tears (AT) in one eye and DQS in the fellow eye, in a masked manner. The central lower tear meniscus radius (TMR) curvature was measured before and at 15 min after instillation by video-meniscometry. Simultaneously, all patients self-evaluated their symptoms of wetness and stinging using a visual analog scale (VAS, in millimeters). Results Topical instillation of DQS significantly increased the TMR at 15 min (mean: 0.21 ± 0.08 (SD) mm) compared with at baseline (mean: 0.16 ± 0.07 mm) (Po0.001, paired t-test), whereas AT had no effect at baseline (mean: 0.18 ± 0.09 mm) or at 15 min (mean: 0.18 ± 0.09 mm). The visual VAS score of wetness at 15-min post-instillation increased in both groups compared with at baseline. In the DQS-treated eyes, the postinstillation change in TMR from baseline was not correlated with the baseline value of the Schirmer test, corneal staining score, or conjunctival staining score. Conclusions Topical instillation of DQS increased aqueous tear volume on the ocular surface of dry-eye patients with SS, with its action being independent of lacrimal gland function.