This investigation was undertaken in order to experimentally reassess the value of myocardial waviness and stretching as early histological indicators of acute myocardial infarction. Twenty three dogs were subjected to periods of ischemia, from 30 minutes to 4 hours; wavy fibers were present in 87% and 91% of the ischemic and non-ischemic samples respectively. It is concluded that myocardial fiber waviness lacks significance as an indicator or early myocardial infarction, whose diagnosis remains a major challenge.