The effects of the mineral elements, calcium and available phosphorus (aP), and the electrolytes, sodium, potassium and chloride in the diet on the growth and physiology of male broiler-type chickens were investigated. The concepts of total dietary cation-anion and electrolyte (Na + K - Cl, meq/kg) balance were compared for their ability to describe observed growth and various parameters to 42 d of age. There were 12 dietary treatments; each was given to four replicates of 32 birds housed in a deep-litter, environmentally controlled shed. Diets were nutritionally adequate and were based on practical ingredients. Total cation-anion balance was varied from 327 to 700 meq/kg and electrolyte balance, from -29 to 553 meq/kg. Results showed that total dietary cation-anion balance did not describe the growth of chickens as well as electrolyte balance. Low (less than 180 meq/kg) or high (greater than 300 meq/kg) electrolyte balance in a diet led to depressed liveweight at 42 d of age. There was an optimum electrolyte balance from 250 to 300 meq/kg. The extent of liveweight depression from feeding diets with an electrolyte balance greater than 300 meq/kg depended on the type of cation added to the diet (Na or K): the range of the Na:K ratio for optimum growth was 0.5-1.8. Acid-base balance was influenced mainly by a diet with a low electrolyte balance (-29 meq/kg). Plasma ion levels (Ca, inorganic P, Mg, Na, K, Cl) were unaffected by dietary treatment, except that high dietary calcium reduced plasma inorganic P levels. Increasing calcium from 1.30 to 1.74% reduced liveweight at 42 d of age by 5%, but subsequent increases up to 2.30% Ca had relatively minor effects. Liveweight tended to be lower for birds fed a diet containing 1.30% Ca and 0.81% aP compared to 0.45% aP with 1.30% Ca. Total cation-anion balance cannot be used in preference to dietary electrolyte balance to describe growth of broiler chickens. However, even though there was a good relationship between growth and dietary electrolyte balance, there were specific cation effects (Na and K) independent of electrolyte balance.