The study aimed to estimate the number of patients with rheumatoid arthritis (RA) that were eligible for therapy with biological disease-modifying antirheumatic drugs (bDMARDs). An observational analysis was performed based on administrative databases of a pool of Local Health Units from Lombardy, Veneto and Apulia region. Data were then projected to the Italian population. Included patients had a RA diagnosis defined by hospitalization discharge diagnosis(ICD9=714) and/or exemption code(006) during 01/01/2013 to 31/12/2017. The criteria applied to evaluate RA patients eligible for bDMARDs were i)treatment failure with methotrexate(MTX) for at least 6 months and start of a different conventional synthetic csDMARD, ii)corticosteroid (ATC=H02) treatment for at least 6 months, dosage ≥7.5mg/die, iii)contraindication to MTX therapy [in therapy or hospitalized for renal damage (ICD9=580-589)/interstizial lung disease (ICD9=510-519)/hepatic failure (ICD9=570-573)]. Considering the Italian population in 2017(n=60,589,445), 318,328 RA patients were estimated. Of them, 43,361 received bDMARDs, 274,967 were not bDMARDs-treated patients. Among the latter, 26,487(9.6%) patients met one or more criteria applied for bDMARDs eligibility. Concerning patients with one criterium, 1,896(0.7%) had MTX-treatment failure and were treated with another csDMARDs, 15,833(5.8%) were in therapy with corticosteroid ≥7.5mg/die, 7,788(2.8%) had MTX contraindication. Regarding patients with 2 criteria, 107 had MTX-treatment failure followed by another csDMARDs and corticosteroid ≥7.5mg/die therapy, 53 were treated with another csDMARDs after MTX-treatment failure and also presented MTX contraindication, 810(0.3%) were in therapy with corticosteroid ≥7.5mg/die and MTX contraindicated. A similar trend was also observed when corticosteroid dosage ≥5mg/die was considered. In patients eligible for bDMARDs, most populated age ranges in both genders were 70-79, 60-69, 50-59 (9%,8.1%,5.5% in men and 21.6%,15.4%,11.3% in women, respectively). This study provided an estimate of RA patients eligible for bDMARDs treatments. Our findings indicated that 9.6% of 274,967 RA patients not currently treated with bDMARDs presented one or more criteria considered for bDMARDs eligibility.