We define in ℂⁿ the concepts of algebraic currents and Liouville currents, thus extending the concepts of algebraic complex subsets and Liouville subsets. After having shown that every algebraic current is Liouville, we characterize those positive closed currents on ℂⁿ which are algebraic. Let T be a closed positive current on ℂⁿ. We give sufficient conditions, relating to the growth of the projective mass of T, so that T is Liouville. These results generalize those previously obtained by N. Sibony and P. M. Wong, and K. Takegoshi in the geometrical case, i.e. when T=[X] is the current of integration on an analytical complex subset of ℂⁿ.