Intracellular Cd[2+], Na[+] and K[+] contents were determined with Cd[2+] -treated and -untreated cells of Pseudomonas sp. No. 40. The K[+] content of the cells grown in 3M NaCl SGC medium (Sehgal and Gibbons complex medium) with 1,500ppm or 2,000ppm CdCl was almost the same as that of the cells cultivated in 3M NaCl SGC medium without CdCl, whereas remarkable decrease of K[+] content was found in the cells grown in 1M NaCl SGC medium with 500ppm or 1,500ppm CdCl. The same results were obtained with the untreated cells suspended in 1M or 3M NaCl SGC medium with 1,500ppm CdCl with 60 min incubation. Viabilities of the cells were remarkably decreased by Cd[2+] in 1M NaCl buffer. However, they recovered their viabilities with the addition of Na-glutamate to the buffer as an energy source. Consequently, the physiological adaptation of strain No.40 to Cd[2+] was also found in 1M NaCl buffer, in the presence of Na-glutamate.