The question, Is adrenal gland weight a useful index of adrenocortical secretion rate?, is answered by correlation analysis of gland weights and secretion rates in California ground squirrels. The weights and rates had a highly significant correlation coefficient of 0.75 in a combined sample of 12 females and 17 males. For the sexes separately the coefficients were significant at 0.55 and 0.56 respectively. Neither the correlation nor the regression coefficients showed any significant sex differences. A graph is presented showing sample sizs of adrenal weights required to distinguish mean differences in secretion rates at given confidence levels. It is concluded that gland weight is a useful index of secretion rate under steady state or slowly changing conditions. Apparent contradictions to this conclusion in the literature are resolved in discussion.