Remote sensing of ocean color, applied to the estimation of chlorophyll biomass, is discussed for the case where the vertical distribution of phytoplankton pigments is nonuniform. Using a spectral model of reflectance, the consequences of vertical structure are evaluated by sensitivity analysis on a generalized pigment profile. It is shown that the assumption of a vertically homogeneous chlorophyll distribution can lead to significant errors (relative error exceeding 100%) in the estimation from satellite data of photic depth and total pigment content in the photic zone. The errors are shown to be functions of the parameters of the pigment profile. It is further shown that, if the shape of the pigment profile is known from independent data, the entire pigment profile may be recovered from the satellite data by making slight changes in the existing algorithms for chlorophyll retrieval.