When cell extracts from Ehrlich ascites tumor cells were assayed for isopentenyl adenine content and correlation with cell growth stage by radioimmunoassay, concentrations of low statistical significance were obtained. High performance liquid chromatographic analysis of cell extracts showed undetectable levels of isopentenyl adenine or 8-hydroxy-isopentenyl adenine, a known metabolite. Thus these substances do not seem to be required for cell division in Ehrlich ascites tumor cells.