X-ray microanalysis of cells in culture is being used increasingly for the study of relationships between element (ion) content and cell function. There is, however, no one single method which can be used for the preparation of all different cell types for study by microanalysis. Cells in suspension are usually concentrated by centrifugation, before cryofixation, cryosectioning, and freeze drying. On the other hand cells grown as monolayers are more often studied as whole cell mounts, which are washed to remove the external medium before cryofixation and freeze drying. The alternative approach, sectioning of cell monolayers is rarely used. Some of the difficulties encountered in preparing and monolayers of smooth muscle cells for X-ray microanalysis are discussed here.