Abstract: In this article, we have elaborated a study over the
nature of financial intermediation in Islamic banks by comparison to
those of conventional ones. We have found a striking difference
between two kinds of intermediation. We tried, from another side, to
study the relationship between the capital level and deficiency risk
relying on econometric model, and we have obtained a positive and
significant relation between the capital and the deficiency risk for the
conventional banks. This means that when the capital of these banks
increases, the deficiency risk increases as well. In return, since the
Islamic banks are constrained to respect the Sharia Committee as well
as customers’ demands that may, in certain contracts, choose to
invest their capitals in projects they are interested in. These
constraints have as effects to reduce the deficiency risk even when
the capital increases.