The theory for an asymmetric Langmuir probe is developed for the case of a collisionless streaming high‐density (ai>Rp>30&lgr;d) plasma withTi<Te. The results are used to analyze the response of the probe to a mildly turbulent drifting plasma. Ion saturation current is a function of the angle between the streaming direction and the probe asymmetry axis and has the formVdi=(Te/Ti)1/2(Vs/4)(&Dgr;Isi/Isi).The operation of the probe is verified by measurements of a known plasma‐drift velocity and found to be accurate within a factor of three.