Background-The present substudy of a recently published randomized trial aimed to investigate the effect of intramyocardial bone marrow cell injection on diastolic function in patients with chronic myocardial ischemia. Methods and Results-In a total of 50 patients, diastolic function was evaluated before and 3 months after bone marrow cell injection using standard echocardiography and strain analysis. In addition, MRI-derived transmitral flow measurements were obtained in a subset of 36 patients. Left ventricular ejection fraction increased from 50 +/- 5% to 54 +/- 7% in the bone marrow cell group, which was a significant improvement as compared with the placebo group (52 +/- 5% versus 51 +/- 7%, P=0.001). Filling pressure estimate E/E' ratio improved from 14 +/- 5 at baseline to 12 +/- 4 at 3 months in the bone marrow cell group, whereas no improvement was observed in the placebo group (13 +/- 4 versus 13 +/- 5). The improvement in E/E' ratio was significantly larger in the bone marrow cell group (P=0.008). Furthermore, the E/A peak flow ratio as assessed by MRI showed a significant increase in the bone marrow cell group as compared with the placebo group (+0.16 +/- 0.25 versus -0.04 +/- 0.21, P=0.01), which was mainly related to an increase in the early (E) peak flow rate in the bone marrow cell group (from 407 +/- 96 mL/s to 468 +/- 110 mL/s, P=0.009 as compared with the placebo group). Conclusions-The current study demonstrates that intramyocardial bone marrow cell injection is associated with a beneficial effect on myocardial relaxation and filling pressures in patients with chronic myocardial ischemia.