Observations of interplanetary scintillation on 32 radio sources over a period of 8 months indicate the presence of enhanced scintillation sectors which usually persist for one solar rotation or longer. The sectors are aligned along the spiral magnetic field over distances of 0.5−1.3 a.u. from the Sun and have a typical width of 3 days at the Earth. Enhanced scintillation sectors lead high solar wind velocity streams by about 3 days and may be associated with enhanced plasma density regions detected by space craft. The sectors extend to heliocentric latitudes of 50° and give some evidence of shearing caused by differential rotation. Observations of the power spectrum of the scintillations confirm that the size of the irregularities which cause scintillation increases as the solar wind increases. This result, and an observed correlation of the spectrum width and scintillation index, provides evidence that the irregularity scale is related to the ion gyroradius.