OBJECTIVE: to identify the echoicity and heterogeneity of carotid plaques associated with ipsilateral symptomatic and asymptomatic neurovascular presentations. Design: cross-sectional study. MATERIALS: a total of 113 patients, with 127 symptomatic and asymptomatic plaques, were studied. METHODS: the duplex images of the plaques were analysed echoically in a computer by means of Grey Scale Median (GSM) [hypoechoic (low GSM), hyperechoic (high GSM)]. The presence or absence of at least two plaque regions within the plaque area being echoically uniform (no variation of echoicity), occupying each at least 10% of the plaque area and having GSM difference greater than the plaque GSM was evaluated to distinguish the heterogeneous (presence of this pattern) from the homogeneous (absence of this pattern) plaques. RESULTS: the symptomatic status was associated with plaques of low median GSM (10.5) and 88% prevalence of the homogeneous pattern as contrasted with the asymptomatic status that was associated with high median GSM (28) and 65% prevalence of the homogeneous pattern [(p=0.001 (GSM), p=0.003 (heterogeneity)]. CONCLUSIONS: symptomatic plaques were associated with hypoechoic and predominant homogeneous echo-pattern whereas the asymptomatic ones were associated with hyperechoic and less predominant homogeneous pattern. Copyright 2001 Harcourt Publishers Limited.