1. We have measured the eosinophil count (eo), eosinophil cationic protein(ECP). Interleukin 5 (IL5), and intercellular-adhesion -molecule (ICAM-1, in children with different stages of asthma (A), to characterize the severity of the disease. 2. 35 healthy non atopic controls (c), 47 atopic children with A, 25 of whom without present complaints (wpc), 13 with present complaints of A(pc), 9 without present complaints but on inhaled steroid therapy (wpcs). 3. ECP: Kabi Pharmacia FEIA; IL-5 and ICAM-1 R & D system immunoassay. 4. Eo was highest in pc group; ICAM-1 (geom mean ng/ml) 340.9 (c), 331.5 (wpc), 345.7 (pc), 527.6 (wpcs). We found a significant correlation between eo and ICAM-1 in the whole examined population (c + A) (p = 0.008). ECP and ICAM-1 have the highest level in wpcs group. Wpcs group shows a higher level of ICAM-1 than c (p < 0.0001), wpc (p < 0.0001), and pc (p < 0.001) group, and wpcs has a significant higher level of ECP compared to wpc group (p< 0.05). 5. Eo count is higher in all groups of A than in c group, but there is no difference among the wpc, pc and wpcs. The group of moderate or severe A patients who need antinflammatory inhaled steroid treatment, differ from the other groups of A on the basis of ICAM-1 and its level of ECP differs from the complaint free patients - who do not need profilactic treatment.