Objective-To establish the frequency of connective tissue diseases (CTD) in a cohort of Italian patients with primary biliary cirrhosis (PBC) and to evaluate the availability of a marker for the early identification of the more common associated CTD. Methods-One hundred and seventy consecutive patients with histologically diagnosed PBC were screened for the presence of a CTD and/or Raynaud's phenomenon (RP). Patients were classified as having a CTD only if they fulfilled standardised criteria. Results-Forty seven patients had a CTD. The most common CTD was systemic sclerosis (SSc), found in 21 patients. RP was present in 54 patients, most of whom (n=39) had an associated CTD. The most prevalent autoantibodies included antinuclear antibodies (ANA) with anticentromere (ACA) and speckled patterns (34 and 33 patients, respectively) and extractable nuclear antigens (ENA, 27 patients). However, while the frequencies of ACA and ENA were significantly higher in patients with an associated CTD (p<0.0001 and p<0.005, respectively), no relationship was found for speckled ANA. ACA was the best predictor of a CTD in patients with PBC (odds ratio (OR) 24.5, 95% CI 5.5 to 108.8), followed by the presence of ENA (OR 23.9, 95% CI 5.6 to 101.0) and RP (OR 20.2, 95% CI 5.7 to 71.2). Conclusions-Using strict standardised classification criteria we have found that SSc is the most common CTD associated with PBC and that ACA and ENA are strong markers for an associated CTD in patients with PBC.