Foreign bodies are usually detected at the first visit. However, they may be overlooked sometimes, especially in children, and may cause some clinical conditions including unilateral relapsing conjunctivitis. A five-year-old girl was presented to the emergency clinic of our hospital with epiphora, purulent discharge, eyelid swelling, and a foreign body feeling in her right eye. The symptoms had been present for one year, and the patient was treated for relapsing conjunctivitis. In slit lamp examination performed with difficulty because of the patient's lack of cooperation, a localized edema and erythema were observed under the right eyelid. An exploration under general anesthesia was planned, and a 1.5 cm-long subconjunctival grass inflorescence was removed. An unknown subconjunctival foreign body should be considered in each patient with relapsing conjunctivitis, especially in children, even in the absence of ocular trauma.