Presence of foreign bodies in the paranasal sinuses are not common findings. Many cases have been reported so far with foreign bodies like dental amalgam, chopsticks, gutta percha pellets, tooth, glue and even bullets. However, presence of foreign bodies in the maxillary sinus as a result of penetrating trauma is uncommon. Most of them have been the results of trauma after vehicle accidents, gunshot injuries and assaults. There are two treatment options – endoscopic and open surgical approach for the removal of sinus foreign bodies. We present a rare case of the transfacial penetrating injuries of maxillary sinus caused by a knife. Introduction; Maxillary sinus foreign bodies account for about 50% of the foreign bodies in the paranasal sinues. They usually have a dental origin (1) like tooth (2), dental amalgam (3), gutta percha points (4), titanium implants (5,6), dental bur (7,8), dental paste (9) and dental impression materials(10). Non-dental foreign bodies like lead pencil (11), broken handle of scooter (12), plastic tubes (13), bullet (radiopaque) (14), rubber bullet (15), air gun pellets (16,17,18,19), ribbon gauze (20), cigarette pipe stem (21), bunch of hair (22), glass (23), piece of glass cylinder (24), plastic chair glide (25), sand (26), stone (27), wood (28), matchstick (29), ballpoint pen (30) penetrating metal bodies like metal door handle (31), sewing needle (32), base of wrist watch (33) and knife (34,35,36) have also been reported in maxillary sinus.