Abstract: The nature, type and quantity of the waxes present in the crudes, as well as wax crystal morphology are the key factors influenced on the flow properties of waxy crude, and their influences on the crudes rhe-ology are summarized in this paper. Wax dissolution temperature is generally higher than corresponding wax appearance temperature 10℃. Above the wax appearance temperature, the crude, although chemically very complex, is a simple Newtonian fluid. The temperature dependence in the Newtonian range is most often adequately expressed by Watther empirical equation or Arrhenius exponential equation. It is demonstrated that the real factor which directly determines the crude rheology is the amount of crystallized wax, riot the wax content. It is established that the pour point is reached when approximately 1m % of wax contained in the crude have precipitated, and about 2m% precipitated wax is sufficient to cause oil gelling. Wax crystal morphology has a significant influence on the crude rheology, but their correlation is still limited to the qualitative range. The quantitative relationship between them should be developed in the further studies.