Biological drugs are used in the treatment of active inflammatory athritides refractory to conventional treatment. Data from the Finnish registry of biological treatment (ROB-FIN) indicates that the effectiveness of the biologicals in clinical practice corresponds to or even excels that of randomized controlled clinical trials, and seems to endure in patients continuing treatment. About one-fifth of rheumatoid arthritis patients discontinue treatment due to lack of effectiveness, and one-tenth due to adverse events. Serious adverse events were seen in 2.5% of all patients. In the future electronic follow-up, pharmacogenetics, and biomarker research may help to better optimize treatment individually.