  We consider the one-loop renormalization of dimension four composite
operators and the energy-momentum tensor in noncommutative \phi^4 scalar field
theory. Proper operator bases are constructed and it is proved that the bare
composite operators are expressed via renormalized ones, with the help of a
mixing matrix, whose explicit form is calculated. The corresponding matrix
elements turn out to differ from the commutative theory. The canonically
defined energy-momentum tensor is not finite and must be replaced by the
"improved" one, in order to provide finiteness. The suitable "improving" terms
are found.
