<正> To test the possible influence of hydrocortisone on the inhibitory effect of interleukin-1 on the pancreatic beta-cell function, insulin release and insulin content of newborn rat islets incubated without or with interleukin-1 and/or hydroc-ortisone were measured. Interleukin-1 （500 ng/1） resulted in a decrease of insulin release during day 1～3, but a partial recovery from inhibition during days 4～7. The insulin content of the islets was not changed significantly. Hydrocortisone had an inhibitory effect on insulin release (at 10-7 M) or both insulin release and insulin content of islets (at 10-6 M). Both 10-7 and 10-6 M hydrocortisone seem to prevent the initial decrease in insulin release exerted by interleukin-1 （500 ng/1） during day 1-3,but thereafter resulted in an even more marked decrease of insulin release correspon-ding to 51% (at 10-7 M) or 25% (at 10-6 M) of control islets, respectively, duringdays 4～7. Rebound of insulin release after interleukin-1 was not seen. Insulin c
