Long eyelashes may be congenital, acquired in association with certain systemic diseases, or drug induced. In the past, long eyelashes were considered an external sign found in children with allergic diseases. However, this claim has never been examined in a controlled study. We compared the eyelash lengths of allergic children and adolescents with perennial allergic rhinitis, with or without bronchial asthma and atopic dermatitis (n = 60) to those of age- and sex-matched nonallergic controls (n = 80). The eyelashes of the allergic patients were found to be significantly longer than those of the controls: 9.43 ± 1.39 mm versus 8.45 ± 1.30 mm (p < 0.001). Eyelash length did not differ between patients with allergic rhinitis only (n = 31 ; 9.65 ± 1.43 mm) and patients with allergic rhinitis and other allergic diseases (n = 29; 9.19 ± 1.31 mm) (p = 0.196). These results indicate that children and adolescents with allergic diseases have longer eyelashes compared to non-atopic controls and that long eyelashes may be a part of the phenotype of the allergic patient.