Functional scintigrams of the heart were performed in 63 patients using different injection techniques and two radiopharmaceuticals (99mTc-pertechnitate and 99mTc-human serum albumen). A comparison of the results shows that injection of 99mTc-human serum albumen into the femoral vein gave the best results. Injection of the tracer into the femoral vein causes less dilution of the bolus than the usual injection technique into the cubital vein. There is less recirculation of the indicator resulting in lower co-efficients of variation of the quantitative parameters. The choice of 99mTc-human serum albumen facilitates demarcation of the individual cardiac chambers.