The use of disclosure index to quantify disclosure level had been widely used in previous studies related to disclosure determinates and disclosure effects. Disclosure indexes rely on totalling items disclosed in an information channel may offer a greater picture about the quantity of information disclosed but little on the quality level, especially when considering that items disclosed may not be consistent from one year to another.The aim of this paper is to introduce an alternative approach to quantify disclosure level through probabilistic measure derived from entropy, named Modified entropy score (MES). A measure which combines both items disclosed and their probability to capture the quality of information disclosed. The introduced measure was compared with previous measure, conventional disclosure score (CDS). The results showed great consistency between the two measures. Disclosure level as measured by both CDS and MES was influenced positively by several firms’ fundamental variables including size, age, liquidity and profitability while ownership dispersion showed insignificant effect on disclosure level.