The prevalence of food allergies is increasing. Concurrently, the average maternal age at birth is also increasing. We conducted a preliminary study to evaluate whether maternal age at the time of delivery is associated with a food allergy in children. Case and control patients were identified among consecutive patients seen by one of us (AD) in the Allergy/Immunology program at the Children's Hospital Boston between 11/1/98 and 2/28/00. Case patients were born in Massachusetts and had evidence of clinical sensitivity and IgE to one or more food allergens (n = 58). Control patients were those born in Massachusetts who had a negative skin test and/or RAST to inhalant and/or food allergens (n = 96). A second comparison group consisted of all live births in Massachusetts in 1999 (n = 80,866). Information on maternal age at birth was missing from 3/58 (5%) of patients with a food allergy and 4/96 (4%) of the control patients, so these patients were not included in the analysis. The proportion of children whose mother was aged 30 and over at their birth was significantly higher in children with a food allergy than control patients (78% vs. 55% p = 0.005) and higher than all births in Massachusetts (78% vs. 53% p = 0.0002). Mothers of children with a food allergy had about three times greater odds of being aged 30 or over at the time of delivery than mothers in either of the comparison groups. Further exploration of the data using logistic regression showed that maternal age over 30 at delivery and being first born were independent predictors of the child having a food allergy. In this study, the presence of a food allergy in children was related to older maternal age at delivery. Additional studies are needed to further evaluate this relationship and its potential implication in preventive strategies for food allergies in children.