The objective was to estimate the incidence of serious infections in the patients treated with anti-TNFalpha agents for rheumatoid arthritis (RA) recorded in the Lombardy Rheumatology Network (LORHEN) registry. The study inclusion criteria were met by 1064 of the 1114 patients with long-standing RA, 519 treated with infliximab, 303 with adalimumab, and 242 with etanercept; their mean age was 55.8 years and the mean duration of RA 9.4 years. Seventy-three patients (6.9%) experienced a total of 74 serious infections, an incidence rate for all treatment courses of 35.9 per 1000 patient-years (95% confidence interval [95% CI] 27.66-44.13). Most were lower respiratory tract (34.2%) or skin and soft tissue infections (20.5%). Of the 1064 patients, the 790 treated with anti-TNFalpha after March 2002 underwent screening tests for LTBI; five patients developed active tuberculosis. Three patients died of septic shock. The type of anti-TNFalpha agent did not seem to affect the incidence or site of the infections. Both univariate and multivariate analyses identified age at the start of anti-TNFalpha treatment (p=0.008), baseline erythrocyte sedimentation rate ([ESR] p=0.014), and the concomitant use of corticosteroids (p=0.029) as significant predictors of infections. There was no statistically significant difference in risk between the anti-TNFalpha agents.