Children (n = 110) with seasonal allergic rhinoconjunctivitis were randomized to receive either twice daily 0.05% levocabastine eye drops and nasal spray plus twice daily topical placebos or 2% sodium cromoglycate eye drops and nasal spray four times daily for a period of 4 weeks. Patients were required to use the nasal sprays as directed and the eye drops only when required. The results obtained suggest that topical levocabastine is at least as effective as sodium cromoglycate for the treatment of this condition. After 2 weeks treatment the effect of therapy on nasal symptoms was considered to be excellent or good in 72% of levocabastine-treated patients and 54% of patients on sodium cromoglycate (p = 0.009), with corresponding values for ocular symptoms of 81% and 57% in the two groups, respectively (p < 0.05). Investigator assessments also revealed that the severity of sneezing and lacrimation were significantly lower in the levocabastine group at this time (p < 0.05). After 4 weeks of treatment, patient diary data revealed that levocabastine was at least as effective as sodium cromoglycate with intergroup differences attaining statistical significance in favor of the topical antihistamine for nasal congestion (p < 0.05). Both agents were well-tolerated with no significant differences in the incidence or type of adverse reactions in the two treatment groups.