A technique is described for the quantitative determination of the distributed growth of Saccharomyces cerevisiae immobilized in polyacrylamide gel. Gel specimens were embedded in paraffin or gelatin and paraffin before sectioning and staining. Photomicrographs of specimen sections were enlarged, and cell microcolony volumes were determined as a function of position in the gel by grid transparency analysis. Overall cell densities within the gel were calculated for a quantitative comparison with values measured by a second spectrophotometric method. The results show good agreement and demonstrate the sigmoidal growth of the immobilized cells, reaching a maximum steady-state value. The technique shows promise as a general method for following the transient growth of organisms immobilized within gel particles.