The dogs in groups I, II and III in equal numbers received diatrizoate, iohexol and ioxilan at a dose of 700 mgI/kg intravenously (i.v.) as a bolus, respectively. Blood samples were collected prior to contrast media (CM) administration and thereafter at 3, 15, 30, 60, 90 and 180 min to evaluate acid-base, venous blood gas status (pH, PCO2, PO2, HCO, BE, O2) and electrolytes (Na+, Ca++, K+). Values of pH, PCO2, BE, HCO, Na+ and K+ remained unchanged or within non-significant fluctuations compared with the baseline values. PO2 was significantly different from the baseline values in group 1 up to 90 min after administration, significant alterations were found for O2 saturation in group 1 up to 90 min, and in group II at 3, 60 and 180 min; and for Ca++ in group 1 at all time points except at 90 min, and groups II and II at 3 and 15 min post administration. It was concluded that none of the CM are considered to cause long-lasting and major effects on acid-base, blood gas and electrolyte status.