In this paper, the unboundedness of solutions for the following planar Hamilton system Ju ' = del H(u) + h(t) is discussed, where the function H(u) epsilon C-2 (R-2, R) is positive for u = 0 and is positively (q, p)-quasi-homogeneous of quasi-degree pq, where p > 1 and 1/p + 1/q =1, h : S-1 - R-2 with h epsilon L-infinity (0, 2 pi) is 2 pi-periodic and J is the standard symplectic matrix. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.