Elective left main (LM) stenting is increasingly performed as a valuable alternative to coronary artery bypass grafting. Nevertheless, clinical data are limited to registries, and randomized trials have not been published. Intravascular ultrasound (IVUS) has been recognized as an accurate tool for assessing optimal stent deployment. We hereby report the usefulness of IVUS in defining the interventional strategy in four consecutive patients presenting with severe, symptomatic ostial LM disease, and this in the era of drug-eluting stents. The first two patients were treated by a short drug-eluting stent for a critical LM stenosis as IVUS demonstrated a reference diameter < 3.7 mm. The third patient had a larger reference diameter and was treated with conventional stenting with optimization of the result by IVUS. IVUS was particularly helpful in all patients to confirm accurate stent placement in relation to the LM ostium and bifurcation. In another patient, based on IVUS findings, surgery was preferred. This patient with diabetes as a risk factor presented with comparable angiographic features. IVUS, however, showed diffuse disease without any healthy reference segment in the LM. All stented patients are asymptomatic at 15 +/- 7 months follow-up with negative stress testing. The present observation indicates that IVUS is an essential tool for strategic selection and to optimize percutaneous coronary intervention for LM disease.