Studies suggest that children who start solid foods early are at risk for developing food allergies. Herein, we evaluated the effects of the introduction of peanuts to the diets of children on emerging peanut allergies. Children with allergic rhinitis and asthma were enrolled in the present study and evaluated in four stages. In the first stage, a clinical history was completed for all participants. In the second stage, skin tests were conducted to detect the sensitization to peanuts. In the third stage, the parents were interviewed about the peanut-eating habits of their children. In the fourth stage, children with a convincing history of allergy or a positive peanut skin test result were subjected to an open oral food challenge (OOFC). Three hundred children in four groups were included, 58.2% of the subjects were male, and the mean age was 7.3±3.9 years. The median age of first exposure to peanuts in patients with peanut allergies was greater than that in children without peanut allergies (2 years versus 1 year; p=0.009). The multivariate analysis, including only those children subjected to the OOFC, revealed that the consumption of peanuts after the age of ≥2 years is a risk factor for developing a peanut allergy (odds ratio=8.0, 95% confidence interval 1.3-50.0, p=0.026). The results of the present study showed that the late introduction of peanuts to children increases the risk of developing a peanut allergy.