Several new biological drugs, of which TNFα blockers are being used most extensively, have in recent years been adopted for the treatment of pediatric inflammatory diseases such as juvenile arthritis and associated chronic iritis, and inflammatory bowel diseases. In special situations the children will be prescribed off-label also other drugs affecting cytokines, e.g. IL-1 and IL-6 blockers. Tailoring of the treatment is possible today with the help of drug level measurements and anti-drug antibody determinations. Severe safety hazards associated with biological drug therapy in children are very rare.