The Sensory Organization Test (SOT) of dynamic posturography, a functional test of balance, has a low sensitivity for compensated unilateral peripheral vestibular lesions. Tilting the head 45 degrees laterally during SOT [i.e. lateral heat tilt (LHT) SOT] may better detect such lesions. Normal subjects and vestibular clinic patients were studied using SOT and LHT SOT. Caloric, rotational chair, and oculomotor testing were also performed for patients, in either a double-blind or non-double-blind manner. The results for both patient groups were similar and thus were collapsed. Normative LHT SOT performance ranges were established to be slightly lower than corresponding SOT scores, for subjects aged 20-59 years. Subjects in older age groups performed with similar equilibrium scores in both SOT and LHT SOT. Normal subjects aged 20-59 and 60-69 years performed similarly, whereas those aged 70-79 performed significantly worse. Sensitivity of LHT SOT to unilateral peripheral vestibular lesions was poor (24%). Specificity of LHT SOT from patients having balance-system weakness was 90%. The results of this study indicate that LHT posturography does not facilitate significant discrimination of patients with compensated unilateral peripheral weakness from those without such lesions.