Summary The effects of alterations in the pH, osmotic pressure, and electrolyte concentration of a cysteine-treated nonfat dry milk solids diluter on the livability of bull spermatozoa have been investigated. There were no differences in livability between the two osmotic pressure levels studied (approximately −0.50° C. and −0.70° C.) and no appreciable differences among the pH levels studied (6.2, 6.6, and 7.0). The addition of either 5.0 or 10.0ml. of 0.5 N NaCl solution to 100ml. of diluter resulted in significantly improved livability. A highly significant interaction between pH and electrolyte concentration indicated that higher pH levels require higher levels of electrolytes. Neither the pH nor the osmotic pressure of the diluter changed appreciably during a 12-day storage period. It was concluded that no improvement in spermatozoan livability can be expected by alteration of the pH, osmotic pressure, or buffering capacity of the diluter employed but that the addition of 0.5 N NaCl results in slightly improved livability.