The activity of a number of enzyme systems was compared in trypsinized suspensions of kidney cortex and primary cultures of the suspension grown as monolayers. Severe reduction in levels of acid and alkaline phosphatase, adenosine triphosphatase, succinic dehydrogenase and cytochrome oxidase was seen in the cultured cells. d-Amino oxidase and glucose-6-phosphatase were missing completely, along with the ability to accumulate para-aminohippuric acid. Aerobic glycolysis, on the other hand, suffered no reduction relative to the parent cells, while the activity of the initial reactions of the hexose monophosphate shunt was increased significantly above normal levels. Use of this preparation for study of development and regulation of cellular enzyme patterns seems justified.