Introduction: Single-leg stance test is a simple clinical test for balance assessment, which exists in many versions. The testing conditions (support-surface, visual input) imply the mining of results. Purpose: Purpose of the study was to establish the intra-ratter reliability of certain procedure of a single-leg stance test in healthy young adults. Methods: 36 healthy subjects, aged 18–30 years, performed single-leg stance test according to the principle of clinical test of sensory interaction and balance. Test was repeated after 7 days. Per each test condition, maximal and average values between first and second measurement day were analysed with ANOVA, and ICC was calculated. Results: The results expressed with maximal values were more reliable. On firm surface with eyes open, everyone reached maximal test time. On firm surface with eyes closed, the ICC was 0.49, on compliant surface with eyes open, 0.67, and on compliant surface with eyes closed, 0.33. Conclusion: The intra-ratter reliability of a single-leg stance test on firm surface with eyes closed and on compliant surface with eyes open in assessment of young healthy adults is good.