OBJECTIVES: Rituximab (RTX; MabThera) is available in Argentina for the treatment of rheumatoid arthritis (RA) in patients refractory to tumour necrosis factor (TNF) inhibition. Evidence suggests that response to RTX is influenced by the number of prior TNF inhibitors [1]. This study evaluates the cost-benefit ratio of current biologic therapies and determines the cost-benefit impact of introducing RTX following one or more TNF inhibitors. METHODS: Prices were taken from three different pharmacies, DroFar, Social Congresso, Scienza, Jan 2007 ($US1=$ARS3.12; €1=$ARS4.05). Average annual treatment costs (drug treatment and administration) were determined over a three year period. ACR20 response rate was chosen as the measure of benefit. Using pivotal trial data, unadjusted for different placebo response, the percentage of patients achieving an ACR20 response rate was: RTX+MTX, 58%; INFL+MTX, 50%; ADAL+MTX, 63% and ETAN+MTX, 71%. ACR20 response rates for RTX were 58%, 51% and 42% after an inadequate response to 1, 1.5 and 2 TNF inhibitors respectively. The cost-benefit ratio was calculated as the cost per ACR20 response rate by dividing the average annual treatment cost by the ACR response rate. RESULTS: In a cost-benefit analysis, RTX was found to have the lowest cost (in $ARS) per ACR20 response rate relative to current biologic therapies: RTX+MTX=$58,577; INFL+MTX=$79,038; ADAL+MTX=$83,035 and ETAN+MTX= $84,708. If RTX was introduced following an inadequate response to 1.5 TNF inhibitors the cost-benefit ratio was $66,617 and this increased to $80,892 following 2 prior TNF inhibitors. CONCLUSION: These results confirm that, compared with current biologic agents RTX has the superior cost-benefit profile. The cost-benefit of RTX is maximised the earlier RTX is introduced, ie. following an inadequate response to one prior TNF-inhibitor instead of two. [1] Kremer JM, Tony HP, Tak PP et al. ACR 2006 (Abstract 0133)