In the cucumber (Cucumis sativusL. cv. Straight Eight) cotyledon expansion assay, cytokinin‐stimulated ethylene production was separated from cytokinin‐stimulated growth through the use of potassium and calcium salts. Low concentrations of KC1, which dramatically promoted growth induced by cytokinin, inhibited ethylene evolution, while CaCl2at a concentration that had no effect on growth, strongly promoted the cytokinin‐induced ethylene evolution. In contrast to the growth response, stimulation of ethylene production was not directly related to the presence of potassium or calcium but to their relative concentrations. Concentrations of KCl and CaCl2which promoted ethylene evolution singly, strongly inhibited it when mixed together. Low rates of exogenous ethylene had no effect on the growth response. Both the growth and ethylene responses were found to be general cytokinin phenomena. Cotyledon respiration was promoted by KC1, CaCl2and cytokinin, but its stimulation was not correlated with either growth or ethylene production. In the presence of KClm cytokinin‐induced respiration sharply lowered the content of certain sugars during the large growth response and followed KCl uptake. Analysis of KCl uptake showed that its growth promoting synergism with cytokinin was not due to osmotic