An electrocardiograph sensor positioning device includes a pair of sensor locating members (12,14) that are angularly adjustable with respect to each other to a determinable angular position. Co-operative indicia means (50,72) provided on each of the sensor locating members furnish an indication of the relative angular position therebetween. Each of the sensor locating members defines a plurality of location zones (34,38: 56-64) for positioning of the electrocardiograph sensors and indicia means (40,42,68) are provided alongside the location zone to determine the precise location of the electrocardiograph sensors when they are positioned in the location zones. The electrocardiograph sensor positioning device thus permits the establishment of reference paths on the human anatomy which are used to locate the positions of the electrocardiograph sensors. The size and extent of the reference paths and the pivotal arrangement of one of the sensor locating members permits adaptation of the device to a relativey wide range of anatomical size and shape regardless of sex.