We compared the propofol dose causing loss of verbal response and suppression of bispectral index to 50, between 50 white and 50 black patients, aged 18–65 years. Propofol was administered at 40 mg.kg−1.h−1and reduced to 8 mg.kg−1.h−1 when bispectral index fell to 50. We recorded heart rate and mean arterial pressure for 15 min in total and calculated, for this period, maximal percentage change from baseline for each. A statistician, blinded to patient ethnicity, found mean (SD) propofol dose for loss of verbal response in white and black patients to be 1.41 (0.37) mg.kg−1 and 1.16 (0.25) mg.kg−1, respectively (p < 0.001). Corresponding figures for maximal percentage change in heart rate were 14.1 (12.6) % and 7.5 (14.0) % (p = 0.015). Other differences were non-significant. The dose of propofol required for loss of verbal response, but not for suppression of bispectral index to 50, is lower in black than in white patients.