The accuracy of standard methods in estimating bulky lesions requires validation. We used clinical/computed tomography (CT) evaluation and power Doppler ultrasound (US) to detect bulky disease in 137 consecutive Hodgkin's lymphoma patients, and analyzed the prognostic relevance of each method. Bulky disease was detected by clinical/CT evaluation in 47% of the patients and by power Doppler US in 20%. After treatment, at multivariate analysis power Doppler US-selected bulky disease was the parameter that best correlated with freedom from treatment failure (p<0.001). Power Doppler US, a readily available imaging technique, provides a better prognostic classification by detecting true bulky disease more accurately.