OBJECTIVE To present and assess a surgical technique designed to minimize the known causes of a discharging mastoid cavity. METHODS A temporal bone dissection to establish the anatomical relationships on which the surgical technique is based. A presentation of the proposed surgical technique and a prospective assessment of the technique in twenty consecutive mastoidectomies. METHODS Five temporal bone dissections were performed to establish the relationship between the chorda tympani and the facial nerve when these structures are approached from above. The surgical technique is presented and the mastoid cavities of twenty consecutive patients assessed. The assessment included measurement of the facial ridge height, "kidney-shape" of the cavity, size of the cavity, size of the meatus, and state of the tympanic membrane. RESULTS In the temporal bone dissections the vertical height between the chorda tympani and the facial nerve at 3/9 o'clock was a mean of 2.01 mm. Nineteen of the 20 consecutive mastoid cavities (95%) performed with the presented technique remained well healed and dry. The mean facial ridge height was 2.7 mm at 3/9 o'clock and 4.8 mm at 6 o'clock. The kidney-shaped measurement was 1.45 mm. The mean size of the cavities was 2.6 mm and 18 of the 20 patients (90%) had an intact tympanic membrane. The mean largest diameter of the meatus was 10.1 mm. CONCLUSIONS The surgical technique presented produces a mastoid cavity with a low facial ridge and oval shape. These two factors have been previously identified as important in the outcome of mastoid surgery.