In the work reported here the transition from laminar to nonlaminar flow was investigated as a function of volume fraction of the dispersed phase for a number of synthetic latices. Two instruments, a conicylindrical viscometer and a high pressure capillary viscometer, were used but Reynolds numbers were calculated only with the capillary instrument. It was found that the use of a dispersion viscosity gives a Reynolds number which decreases with increasing volume fraction. However, if one uses the viscosity of the continuous medium, i.e., water, the Reynolds number apparently increases or remains constant. This result is very similar to some results reported on the laminar‐to‐turbulent transition for solutions of poly(acrylic acid) in water.