The use of an expanded bed of STREAMLINE Red H-7B for the purification of the intracellular glycolytic enzyme glucose 6-phosphate dehydrogenase (G6PDH) directly from untreated preparations of disrupted yeast cells has been investigated. Small-scale experiments, carried out in packed beds, have shown that the optimal pH for adsorption is 6.0 and have enabled optimization of elution conditions using a series of eluents. The dynamic capacity of the adsorbent far G6PDH was determined in a small expanded bed to be 28 units/mL. These results were used to develop a preparative scale separation of G6PDH in a STREAMLINE 50 expanded bed column. G6PDH was purified directly from an unclarified yeast homogenate in 99% yield with an average purification factor in the eluted fraction of 103. Cleaning-in-place (CIP) procedures using 0.5 M NaOH and 4M urea in 60% (v/v) ethanol have demonstrated that the adsorbent can be regenerated with no loss of adsorption capacity or alteration of bed expansion characteristics after many cycles of operation.