The use of light scattering to study the structure of colloidal disper
sions under shear is described. An apparatus has been constructed whic
h can collect two-dimensional scattering data from a range of sample e
nvironments, including sheared samples. Shear cells, made of fused qua
rtz, of both the disc/disc and Couette type can be used to collect sca
ttering data from all three principal axes of a flowing dispersion. Th
e shear cells can be driven continuously or in oscillatory motion. Res
ults of scattering experiments on sterically stabilised polymethyl met
hacrylate latices in organic media will be described. These systems ca
n be adjusted so that the refractive index difference between the part
icles and the dispersion medium is small (less than 0.01). This permit
s measurements on concentrated systems up to 50% volume fraction. Data
showing the onset and extent of ordering under shear are presented. T
hese results are discussed in terms of models of 'hard-sphere' fluids.