Little evidence is available on the prevalence of allergic conjunctivitis in pediatric populations. The objective of this study was to assess the cumulative prevalence of allergic conjunctivitis in children with rhinitis, asthma and eczema in a secondary pediatric outpatient clinic. Children aged 5–15 yr referred during the period of 2002–2004 in whom allergic conjunctivitis, asthma, allergic rhinitis or eczema was diagnosed were included in a retrospective survey. At referral patient characteristics, history, symptoms, signs and results of type 1 allergy tests were entered into an electronic form. Four hundred and fifty‐eight children with a mean age of 9.4 yr were studied. Of 316, 324 and 149 children with rhinitis, asthma or eczema, respectively, 133 (42%), 78 (24%) and 45 (30%) had concomitant allergic conjunctivitis. One hundred and thirty‐seven (30%) had allergic conjunctivitis, of whom 133 (97%) also had allergic rhinitis, 77 (56%) asthma and 45 (33%) eczema. One hundred and twenty‐five (91%) of the children with allergic conjunctivitis had positive allergy tests to one or more allergens, sensitization to house dust mites being more frequent in chronic allergic conjunctivitis than in acute allergic conjunctivitis (95% vs. 53%; p < 0.01). Sensitization to grass was more frequent in children with acute allergic conjunctivitis (78% vs. 57%; p = 0.03). In a secondary pediatric outpatient clinic allergic conjunctivitis is a frequent co‐morbidity to allergic rhinitis and to asthma and eczema. Allergic conjunctivitis need to be included as an important co‐morbidity in future guidelines on asthma, rhinitis and eczema management.