Alterations in the immune response play an important role in the pathogenesis of atopic dermatitis (AD). We evaluated the role of Th1/Th2 cytokine imbalance in paediatric AD and its progression towards other allergic manifestations. The levels of total interleukin (IL)-12 (p70+p40), IL-12 p70 and soluble CD30 (sCD30) were measured in paediatric patients affected by AD and in age-matched, non-atopic subjects (controls). The serum levels of total IL-12 and sCD30 were higher in patients than in controls (p=0.003 and p=0.053, respectively). Total IL-12 and sCD30 were also particularly increased in patients with severe disease. Serum levels of total IL-12 were negatively correlated with patient age (p=0.001): they were significantly higher in patients younger than 30 months, as compared to age-matched controls and to older patients and controls. Total IL-12 and sCD30 production were not significantly correlated with disease outcomes (atopic march) or with a family history of atopy. Our data show that total IL-12 levels are strongly associated with Th2 activation and severe disease in children with AD. The increased production of total IL-12 at an early age might indicate a different immune modulation and suggests the possibility of new therapeutic approaches for allergic diseases, in particular AD, early in childhood.