Let ngeq3 and J_{n}:=circ(J_{1},J_{2},...,J_{n}) and j_{n}:=circ(j_{0},j_{1},...,j_{n-1}) be the ntimesn circulant matrices, associated with the nth Jacobsthal number J_{n} and the nth Jacobsthal-Lucas number j_{n}, respectively. The determinants of J_{n} and j_{n} are obtained in terms of the Jacobsthal and Jacobsthal-Lucas numbers. These imply that J_{n} and j_{n} are invertible. We also derive the inverses of J_{n} and j_{n}.