The adhesion and spreading of cells at surfaces are well-established phenomena which have been extensively observed using light or electron microscopy. The kinetics of both processes can be quantitatively measured by allowing the cells to attach themselves to the surface of a planar waveguide. Measuring the effective refractive index of the waveguide allows the number of cells per unit area and a parameter uniquely characterizing their shape, such as the area in contact with the surface, to be determined. Cells suspended in nutrient medium or pure phosphate buffer were allowed to attach to and spread on a metal oxide surface or a layer of fibronectin, and the kinetics of attachment and spreading have been measured. Attachment kinetics are the same in all cases, but spreading on the metal oxide requires nutrient medium, without which it does not occur. Spreading of cells attached to a layer of fibronectin in the absence of nutrient medium occurs at about a tenth of the rate of cells spreading on metal oxide in the presence of nutrient.