1. simple Maddox rod (Franceschetti) 2. set of scaled large diameter Maddox rods 3. synoptophore 4. synoptometer (Cüppers) 5. dark red glass in front of the Harms tangent scale (Kolling). Whereas the first two methods allow to measure in primary position only, the other three also permit secondary and tertiary position measurements. Thirty normal subjects underwent comparative measurements by means of the above techniques in monocular and binocular condition. The median values indicate that all these methods are reliable but that certain specific differences influence the results. For this reason, pre- and postoperative measurements of ocular torsion should always be performed by the same method. The most appropriate techniques have shown to be: the set of scaled Maddox rods for measurements in primary position only, the dark red glass in front of the Harms tangent screen for measuring also in secondary and tertiary positions.