OBJECTIVE: To study the contribution of routine viral screening tests in patients with early rheumatoid arthritis (RA) or a potential for progressing to RA. METHODS: Eight hundred thirteen patients with swelling of at least 2 joints for at least 6 weeks and a symptom duration of less than 6 months in the ESPOIR cohort were screened for parvovirus B19 (IgG and IgM anti-parvovirus B19 antibodies), hepatitis B virus (HBV; hepatitis B surface antigen), hepatitis C virus (HCV; anti-HCV antibodies), and human immunodeficiency virus (HIV; anti-HIV-1 and -2 antibodies). RESULTS: Parvovirus B19 testing was performed in 806 patients and showed longstanding immunity in 574 (71.2%) and no antibodies in 223 (27.7%). Among the 9 remaining patients (7 IgG positive/IgM positive, 1 IgG negative/IgM positive, and 1 IgG indeterminate/IgM positive), only 2 (0.25%; 95% confidence interval [95% CI] 0-0.99%) had a positive polymerase chain reaction test for parvovirus B19; these patients (women ages 34 and 40 years) had no extraarticular signs. HIV seroprevalence was 0.12% (n = 1 of 813; 95% CI 0.01-0.8%) and HCV seroprevalence was 0.86% (n = 7 of 808, 95% CI 0.38-1.86%). HCV-related arthritis was diagnosed in 4 patients (0.5%). HCV-seropositive patients had significantly higher transaminase levels than the other patients (P = 0.001), with no significant differences for the other laboratory data. HBV seroprevalence was 0.12% (n = 1 of 808; 95% CI 0.01-0.8%); the positive HBV status was known before study inclusion, and the patient had no diagnosis of HBV-related arthritis. Finally, routine viral testing identified 2 patients with parvovirus B19 infection and 3 with HBV infection (0.6%; 95% CI 0.2-1.5%). Cost was €85.05 per patient (total €68,720). CONCLUSION: Routine serologic testing did not contribute substantially to the diagnosis in this context.