Different scoring systems have been developed to determine the severity of atopic dermatitis. The SCORAD (SCORing Atopic Dermatitis), one of the best validated systems, is suited for clinical trials, but is too complicated and time consuming for routine clinical use. The TIS score (Three Item Severity score), a simplified system, is based on the evaluation of erythema, oedema/papulation and excoriation on a scale from 0 to 3. In order to determine the value of the TIS score we conducted a prospective study in 126 children with mild to severe atopic dermatitis. Both the TIS score and the SCORAD were assessed by trained investigators. Interobserver agreement was investigated in 20 children by comparing the independently performed scores of three investigators. A positive correlation was found between the TIS score and the SCORAD (Rank Spearman r(s)=0.86; p<0.0005). The item which correlated best with the SCORAD was excoriation (r(s)=0.72; p<0.0005) followed by oedema/papulations (r(s)=0.66; p<0.0005). Interobserver agreement which was calculated by Cohen's kappa (kappa) was "excellent" for SCORAD (kappa=0.82; p<0.001) and "fair" for TIS score (kappa=0.58; p<0.01). We conclude that the TIS score is a rough, though reliable and simple system for scoring atopic dermatitis. It is particularly suitable in general practice, for routine clinical use and for screening purposes in clinical trials. For research purposes, the objective SCORAD offers a more detailed and comprehensive assessment.