Frank lead ECG/VCG changes with deep inspiration, expiration, and body position were investigated in 194 patients, 100 with an old myocardial infarction and the remaining 94 chosen as a representative sample of catheterization laboratory patients with a variety of cardiac conditions. In a subgroup of 144 of the patients, Frank lead records were made both at the fifth and the fourth intercostal space. Diagnostic interpretation was performed using the VA-Pipberger ECG Program. The results indicate that, in general, body position and electrode level influence on mean intervals and orientation angles is negligible. There was a highly significant decrease in the R and Q wave amplitudes in leads X and Z and in the maximum spatial magnitude of QRS when electrodes were shifted from the fifth to the fourth interspace. The most pronounced decrease in ECG/VCG amplitudes took place in deep inspiration while mean orientation angles changed little, with the exception of QRS elevation. However, while mean changes with body position and electrode level were rather small, substantial orientation and magnitude changes took place in many patients. Diagnostic interpretation of the records changed in 12.5% with electrode level change, in 11.9% with the transition of body position, and in 16.8% with deep inspiration. Strict standardization of electrode positions and recording procedure is suggested, particularly when serial comparison of Frank lead records is planned.