Aim To investigate the association between the occurrences of developmental defects of enamel (DDE), in first permanent molars, and bronchodilators and/or corticosteroid intake for asthma-like episodic treatment at preschool age, in 6-12 year old children. Methods Children of the case group (n = 70) were followed in the Paediatric Pulmonary Unit and the Unit of Allergology, Asthma and Inflammation at 'Aghia Sofia' Children's Hospital, Athens, Greece and had used asthma drugs during their first 4 years of life. The control group (n = 70) consisted of healthy children who visited the Postgraduate Paediatric Dental Clinic, University of Athens. Information regarding demographic data, medical history, pregnancy, birth weight, duration of breastfeeding, mother's smoking habits and antibiotic use at preschool age was obtained through a structured questionnaire. Details concerning asthma drugs used were extracted from medical records. The children in both groups underwent an oral examination under standard clinical conditions and all surfaces of first permanent molars were assessed for enamel defects using the modified DDE Index. Chi square statistics, Mann-Whitney U test, Spearman correlation coefficient and logistic regression analysis were used for statistical analysis of the data (p <= 0.05). Results DDE were present in 24 children (34.3%) in the case group and only in 6 (8.6%) in the control, with the difference between the two groups being statistically significant (p < 0.001), while the estimated odds ratio was 5.56. Among the children with DDE in the case group, 41.6% had at least one hypoplastic molar with loss of enamel. The type of asthma drug, age at treatment onset and duration of drug use were not significantly associated with the severity or extent of DDE. Among the possible influential factors, gender was the only statistical significant factor. Conclusions Children treated with asthma drugs for asthma-like episodes at a preschool age showed an overall increased risk for developing enamel defects in their first permanent molars. Severe hypoplastic lesions with loss of enamel was a frequent finding among affected molars.