The modified Lothrop procedure or frontal sinus drill-out is a completely intranasal technique that creates a common frontonasal communication to allow drainage and ventilation of the chronically infected frontal sinus. It is an effective alternative to the classic frontal sinus obliteration. The modified Lothrop is usually performed on an outpatient basis, leaves no external scars, provides excellent visualization of the frontal sinus in the postoperative setting, and yields a high cure rate in chronically infected patients.