Cow milk and milk products are the most common food products consumed in Israel; rates of allergy to cow milk exceed those of peanuts in infants and children. The aim of the present study was to evaluate retrospectively the clinical features and natural course of immunoglobulin (Ig) E-mediated cow milk allergy (CMA) in Israel. Data of children diagnosed with CMA from 1995 to 2003, were collected regarding age at first and most recent reactions, symptoms and signs, family history of atopy, other allergic diseases, emergency department visits, hospitalizations, and treatment. Patients with transient CMA were compared to those with persistent CMA (> or =3 yr old). The study group consisted of 105 patients, 43 with transient CMA (age range: 0.48-11 yr). The remaining 62 patients (age range: 3-16.5 yr) did not achieve tolerance to cow milk during the follow-up period. No differences were found between the groups in mean age and symptoms and signs at the first allergic reaction and family history of atopy. Patients with persistent CMA had a higher rate of asthma than patients with transient CMA (61.2% vs. 18.6%, p < 0.001). Fifty patients with persistent CMA had 137 subsequent allergic reactions after diagnosis, 25% of the reactions were due to oral milk challenge at the clinic and 75% due to accidental exposure, of which 13% required an emergency department visit and 8%, hospitalization. Only 19% of the reactions were treated with epinephrine injection. In conclusion, in our experience, less than half of the children diagnosed with IgE-mediated CMA during 9 yr, outgrew it. The patients with persistent CMA have a higher prevalence of asthma compared with the general population or to children with transient CMA. The high number of recurrent allergic reactions due to accidental exposure and the low rate of epinephrine usage in these patients point to a need for better education of patients and their families.