This study was performed to assess the impact of precise timing and the repeatability of the simplified 10-min 14C-urea breath test. Thirty-three patients underwent a 14C-urea breath test at 10 and 12 min (test I) and after 24 h (test II). The paired t-test was applied to assess differences between two successive measurements at 10 and 12 min, and the method of Bland and Altman was used to evaluate the repeatability of the test. Only test I (P = 0.004) showed a significant difference between two successive measurements at 10 and 12 min. The coefficients of repeatability at 10 and 12 min were 1.54 and 1.48, respectively. No bias was found. From this study, we can conclude that breath collections, delayed by 2 min (20% error), have no impact on the clinical interpretation of the results. The repeatability of the simplified 10-min 14C-urea breath test is sufficient for clinical use.