A new stability test for d-dimensional systems is presented. It consists of maximizing the minimum eigenvalue of a positive definite Gram matrix associated with a polynomial positive on the unit d-circle. This formulation is based on expressing the polynomial as a sum of squares and leads to a semidefinite programming (SDP) problem, which can be solved reliably. Although the test is based on a sufficient condition, the practical results are very good. Also, the test has the advantage of not giving false positives.