  A study of the thermodynamics in IIA Matrix String Theory is presented. The
free string limit is calculated and seen to exactly reproduce the usual result.
When energies are enough to excite non-perturbative objects like D-particles
and specially membranes, the situation changes because they add a large number
of degrees of freedom that do not appear at low energies. There seems to be a
negative specific heat (even in the Microcanonical Ensemble) that moves the
asymptotic temperature to zero. Besides, the mechanism of interaction and
attachment of open strings to D-particles and D-membranes is analyzed.
