Parental education is important in managing childhood atopic dermatitis (AD). We evaluated the long-term effects of a 2-day parental education program (PEP) on childhood AD. In an investigator-blinded, randomized controlled trial, 59 children age 6 months to 6 years with moderate to severe AD and their mothers were recruited in Japan. Participants were given a booklet about AD and received conventional treatment alone or in combination with a 2-day PEP comprising three lectures, three practical sessions, and a group discussion. The primary outcome was evaluation of eczema severity using SCORing Atopic Dermatitis (SCORAD) at 6 months. Secondary outcomes included changes in symptom scores, amount of corticosteroid used, parental quality of life as determined according to the Dermatitis Family Impact questionnaire, and change in parental anxiety regarding the use of corticosteroids in their children. Participants in the PEP group had a significantly lower SCORAD score than those in the control group at 6 months (mean difference 10.0, 95% confidence interval [CI] = 2.3–17.7, p = 0.01) and objective SCORAD score (mean difference 7.1, 95% CI = 0.8–13.5, p = 0.03). The sleeplessness symptom score (mean difference 1.6, 95% CI = 0.0–3.1, p = 0.048) and corticosteroid anxiety score (p = 0.02) in the PEP group were significantly better than in the control group at 6 months. There was no significant difference between groups in the amount of corticosteroid used or quality of life. The PEP had positive long-term effects on eczema severity and parental anxiety about corticosteroid usage.