Aged 37 year-old male was reported in whom moliodol, on procedure of instillation of contrast medium into the sinus, had gone into the surrounding tissue of the maxillary sinus by technic failure with resulting infections of the surrounding tissue. Fortunately, the patient made a complete recovery without any aequela. I would like to emphasize that procedures causing visualization of the maxillary sinus by instillation of radio-opaque substances are simple, but not without danger, therefore, religions precaution is necessary.