We performed scatter and attenuation compensation in 201Tl myocardial SPECT using the triple-energy-window (TEW) scatter correction method and 99mTc transmission scan (TCT). A dual-headed SPECT gammacamera system equipped with parallel-hole collimators was employed for imaging and a sheet source for TCT was attached to the surface of one of the two detectors. Two imaging protocols, a sequential mode and a simultaneous mode, were examined. In the sequential mode, TCT was performed prior to the administration of the tracer and then ECT was carried out. On the other hand, the injection was followed by a simultaneous transmission-emission scan, in the simultaneous mode. Results of phantom studies showed that reconstructed SPECT values of the whole myocardium were almost equal to the true value with errors of less than 5 per cent, and that more homogeneous images were obtained by performing scatter and attenuation correction. We conclude that this correction method was clinically practical and cost-effective because it uses parallel-hole collimators and does not require fan-beam collimators which may produce truncation artifacts.