The coronary arterial beds from more than 1200 subjects aged 1 to 65 years were investigated by both histopathological, histochemical and morphometric methods. Light microscopic aspects were analysed to reveal if plaque development and progression toward obstructive lesions were associated with arterial wall changes, particularly of the intimal connective tissue adjacent to lesions. Six patterns of plaque development in the coronary arterial tree were delineated, emphasis being placed on the observation that the onset and progression of plaques frequently appeared independent of arterial wall changes, in contrast to fatty streaks, gelatinous lesions, intimal necrotic areas, incorporated microthrombi and intramural thrombi. Our results support the view that plaques develop and progress on their own, superimposed on a preexisting arterial wall microarchitecture.