A novel automated image analysis method is described for characterizing the viability and morphology of animal cells from suspension cultures. With the aid of the exclusion dye Trypan Blue, the total and viable cell counts and the percentage of dead cells present are found. The area, perimeter, equivalent diameter, and circularity of the projected image of each cell are also measured, allowing the estimation of cell volume. The image analysis method is inherently sensitive, precise, consistent (non-operator dependent) and relatively fast, taking approximately 22 min. to analyze one sample. The data it gives on individual cellular activity, as characterized by Trypan Blue uptake and cell morphology, are valuable in allowing early diagnosis of even subtle changes in the health of a culture. The method should permit better optimization of culture conditions, and will provide data for the modeling of cell population dynamics. As the conventional manual method is operator dependent, relatively limited in the amount of information it provides, and has a tendency to underestimate Trypan Blue takeup, it is suggested that image analysis be the preferred option for animal cell counting and viability determinations.