Interstitial lung disease (ILD) has been reported in 3 to 11% of patients with primary Sjögren's syndrome (pSS). The aims of this retrospective multicenter study were to: 1) analyze characteristics and outcome of ILD in pSS; and 2) evaluate predictive factors associated with ILD onset and deterioration. Twenty-one of 263 patients with pSS (8%) developed ILD. ILD onset preceded pSS diagnosis (n=5), was concurrently identified in association with pSS (n=6) and developed after pSS onset (n=9). Presenting ILD manifestations were: acute/subacute (n=11) onset of ILD, symptomatic progressive onset of ILD (n=5), and asymptomatic patients exhibiting abnormalities consistent with ILD on PFTs and HRCT-scan (n=5). ILD therapy included: steroids (n=21), cyclophosphamide (n=1), azathioprine (n=4) and rituximab (n=1). The course of ILD was as follows: improvement (15.8%), stabilization (47.4%) or deterioration (36.8%). Predictive parameters of ILD onset were: older age (p=0.044), Raynaud's phenomenon (p=0.001) and esophageal involvement (p=0.001). Factors associated with ILD deterioration were: older age (p=0.038) and esophageal involvement (p=0.038). Thus, this study underscores the poor outcome of ILD during pSS; thus, systematic screening of pulmonary involvement is required in pSS patients, resulting in both diagnosis and management at early stage of ILD. We also suggest that patients presenting predictive factors of ILD deterioration may need a closer follow-up and a more aggressive therapy.