Successive estimation of B-glucuronidase, a lysosomal acid hydrolase was carried out in 20 cases of pemphigus, before and after,, administering corticostcroid, which is the drug of choice in the treatment of pemphigus. It Ls observed that there is significant decrease in this enzyme activity, when the lysosomal membrane stability' is maintained by adequate dosage of corticosteroids. The value of successive estimation of B- glucuronidase is discussed and the enzyme activity is suggested as a biochemical marker in assessing the response to treatment as well as maintainence therapy with corticosteroid.