OBJECTIVES: The aim of the Costi-&-Outcomes-in-Dermatite-Atopica (CODA) study was to evaluate the socioeconomic impact of AD. METHODS: the CODA study was a naturalistic, multicentre, longitudinal ambispective (retro-prospective), prevalence based Cost Of Illness study. Data on patients with moderate or severe AD enrolled during flare-up was collected: socio-demographic, clinical (SCORing-Atopic-Dermatitis index (SCORAD): 0=no disease; 100=maximum manifestation) economic (direct and indirect costs), HRQoL (intangible costs), preferences towards pharmacological treatment. The following results pertain to the economic burden of AD and its treatment in adult patients. The analysis was conducted from the societal perspective with a 3 month time horizon. Direct medical costs (hospitalizations, drugs, cosmetics, personal health supplies, specialist visits, diagnostics and laboratory exams) were quantified using prices or tariffs expressed in Euro 2005. Also indirect cost, in terms of productivity losses by patients, were calculated using human capital approach. RESULTS: we enrolled 104 valid adults from 6 Italian dermatological referral centres (males 53.8%, mean age=32.9±11.8 y.o.). At the enrolment the median SCORAD was 52.0 while after 2 months was 18.0 (p<0.0001 Wilcoxon Signed Rank test). Direct cost/patient/month was at baseline 369.6±440.0€: 28.8% hospitalizations, 19.9% drugs, 16.0% cosmetics. After 2 months from the enrolment direct cost/patient/month was €188.1±€236.1: 42.5% drugs, 35.2% cosmetics, 8.8% hospitalizations. The decrease in direct cost during the follow up period was statistically significant (p=<0.0001 paired samples t test). Indirect cost/patient/month was €247.0±€626.5 at baseline and €32.8±€106.1 after 2 months (p=<0.0001). CONCLUSION: this is the first study evaluating the socio-economic impact of AD in Italy. The difference between cost during relapse period and after 2 months is significant. Among adult patients hospitalisations and drugs are the cost drivers at baseline and after 2 months respectively. High cost and the sensitive impairment of quality of life significantly contribute to the high socioeconomic burden of AD.