Purpose <p>This study sought to investigate the presence of residual myocardial hyperemia on the recovery phase in patients undergoing stress CMR.</p> Material and methods <p>Fifty patients with clinical indication for stress CMR underwent quantitative perfusion imaging in resting conditions, after regadenoson-induced hyperemia (400 mcg, 5&#xa0;mL), and 10&#xa0;min after recovery with euphylline. Studies showing hypoperfusion due to ischemia and/or prior myocardial infarction were excluded. Global myocardial blood flow during rest (MBF_rest), stress (MBF_stress) and recovery (MBF_recovery) and MPR indices (MPR_stress/rest and MPR_{stress/recovery}) were calculated using automated pixel-wise quantitative myocardial perfusion mapping.</p> Results <p>A total of 30 patients (22 males, mean age of 62.7 ± 1&#xa0;years) were included in the analysis. Global MBF_rest and MBF_stress were 0.83 ± 0.2&#xa0;mL/g/min and 2.1 ± 0.6&#xa0;mL/g/min, respectively. After recovery with euphylline, myocardial perfusion did not return to the resting values (MBF_recovery of 0.92 ± 0.3&#xa0;mL/g/min) and statistically differed from MBF_rest (<i>p</i> &lt; 0.01), suggesting residual myocardial hyperemia. This resulted in an abnormally low MPR_{stress/recovery} (2.43 ± 0.7) with respect to MPR_stress/rest (2.56 ± 0.7) (<i>p</i> = 0.03). A linear mixed-effects model accounting for repeated measures revealed statistically significant group differences over time in global MBF (mean difference 0.1, 95% CI 0.02–0.17, <i>p</i> = 0.01) and global MPR (mean difference −0.13, 95% CI −0.25 to −0.02, <i>p</i> = 0.02).</p> Conclusion <p>Despite the use of euphylline to counteract the vasodilator effect, MBF does not completely revert to resting values and MBF_recovery cannot be used as a substitute for MBF_rest when regadenoson is used. Consequently, a rest/stress protocol is advised for quantitative CMR perfusion to obtain accurate MBF and MPR parameters.</p>