Proton NMR methods can monitor mobile lipids (e.g., fatty acids and glycerides) in intact tissue. Lipids play a major role in cardiac energy production, and elevated levels of myocardial lipids have been reported following an ischemic insult. The present study examines the potential of high‐resolution ¹H NMR spectroscopy to monitor lipid alterations 24 h following coronary occlusion in dogs, and to correlate these finds with regional myocardial blood flow (RMBF) measured by radiolabeled microspheres. The dogs were killed, and samples of excised myocardium were studied by high‐resolution ¹H NMR spectroscopic analysis using solvent suppression in combination with the Hahn spin‐echo pulse sequence. Mobile lipids levels in myocardium with moderate blood flow reduction (28.6 f 7, integral values, arbitrary units; flow 5–50% of control) were significantly elevated compared to the mobile lipid levels in control myocardium (5.3 ± 8, P < 0.001) and in myocardium with severe flow reduction (7.2 ± 10, P < 0.001; flow 5% of control). The mobile lipids in myocardium with severe flow reduction were not elevated significantly relative to control tissue. As anticipated, depression in the level of creatine paralleled the microsphere determined degree of ischemia, i.e., compared to control (9.0 ± 3); creatine levels were moderately decreased with flows 5–50% of control (5.5 ± 4, P < 0.001) and markedly decreased with flows < 5% of control (1.0 ± 2, P < 0.001). This study suggests that high‐resolution ¹H NMR spectroscopy may be used to evaluate alterations in myocardial lipid levels following an ischemic insult. This observation, in addition to changes in other selected metabolites, may provide diagnostic and pathophysiologic insight into the severity of the myocardial injury. © 1987 Academic Press, Inc.