This study aimed to determine intratester and intertester positional reliability in maximum subtalar joint (STJ) pronation, maximum supination and palpated neutral in three planes. Also, to assess the reliability and validity of the assumption that there will be twice as much pronation from STJ neutral as supination (the Root ratio). Two testers measured the feet of 20 subjects. Measurements were made by the Polhemus Isotrak II tracking system which gave high resolution and permitted blinding of testers. Generally, good intratester reliability was described in three positions and three planes of motion (Interclass correlation [ICC] 0.74-0.97). Intertester reliability was generally lower but still acceptable (ICC 0.71-0.88). The validity of the intertester results for pronation and supination is questionable as the two testers measured at significantly different levels. When STJ neutral was determined through palpation, no consistent ratio between eversion and inversion was found. Disadvantages of the ICC as a reliability index are highlighted.