The aim of this study is to retrospectively analyze 10-year drug survival of first-line TNF inhibitor (TNFi) in rheumatoid arthritis (RA), ankylosing spondylitis (AS), psoriatic arthritis (PsA), and juvenile idiopathic arthritis (JIA) patients, comparing withdrawal rates and discontinuation pattern between adult- and juvenile-onset populations. RA, AS, PsA, and JIA patients treated with infliximab, etanercept, or adalimumab as first TNFi between 1999 and 2015 were extracted from a local registry. Drug survival up to 10-year follow-up was evaluated by the Kaplan-Meier method and compared according to age (adult vs juvenile onset), TNFi agent, and discontinuation reason by a stratified log-rank test. Three hundred sixty JIA (205 etanercept, 66 adalimumab, and 89 infliximab) and 951 (607 RA, 188 AS, and 156 PsA) adult patients (464 infliximab, 262 adalimumab, and 225 etanercept) were included. After exclusion of systemic-onset JIA (18.5%), overall 10-year retention rate was 31.8%, with no difference between adult- and juvenile-onset patients (32.1 and 30.2%, respectively; HR 0.938 [95% CI 0.782-1.125]). Etanercept showed the highest drug survival in adult-onset population (p < 0.0001 vs both monoclonal antibodies) and infliximab the lowest in juvenile-onset population (p = 0.005 vs adalimumab and p < 0.0001 vs etanercept). Inefficacy was the most frequent reason for TNFi withdrawal in adult population (29.75%) with a significantly higher risk of discontinuation than in juvenile-onset subgroup (HR 1.390 [95% CI 1.060-1.824]). Serious infections and malignancies caused TNFi withdrawal only in adult whereas gastrointestinal, neuropsychiatric, and ocular complications quite only in juvenile patients. Despite a similar 10-year drug survival, adult- and juvenile-onset subpopulations showed a significantly different pattern of TNFi reasons for discontinuation.