The dynamics of the flow inside an evaporating sessile drop of water with polystyrene spheres of 1μm in diameter is described. The initial volume of the drops is in the range from 0.6 to 1 μl and observations are made from the deposition, up to total evaporation. The flow inside the drop is recorded in a sequence of images that are analyzed with a micro PIV system and image processing to extract quantitative information on the dynamics of the flow and the contact line. The flow has various stages with different space and time scales. The particles move to the contact line to form the coffee ring in periphery of the footprint. Once the drop pulls out from the coffee ring and according to preliminary observations for large concentrations, it is possible to correlate the motion of the fluid inside the drop with the pattern of sediments.