Aggregation of alumina powder in water andn-heptane is followed by turbidimetryin situ.The experiments are carried out under turbulent conditions. They are discussed in the framework of a model which takes into account the hydrodynamic and physicochemical aspects of aggregation. A good agreement between measured and predicted turbidity is found provided the aggregates are considered as noncompact and liable to undergo fragmentation. Recent models of aggregation and fragmentation of fractallike clusters are successfully tested. The aggregate morphology seems to depend on the nature of the liquid medium, however, not on the stirring rate.