A crystalline form of nilotinib L-tartrate selected from: a) Crystalline Form I of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 9.4, 11.7, 12.7, 18.2 and 19.0 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 5; b) Crystalline Form II of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 8.7, 15.7, 17.2, 19.4 and 20.0 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 6; c) Crystalline Form III of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 8.2, 9.1, 12.3, 15.0 and 17.6 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 7; d) Crystalline Form IV of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 13.6, 18.3, 19.5, 21.9 and 24.3 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 8; e) Crystalline Form V of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 3.6, 7.6, 14.1, 17.8 and 19.5 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 9 and f) Crystalline Form VI of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 4.7, 12.1, 16.3, 21.0 and 24.4 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 10. a) Crystalline Form I of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 9.4, 11.7, 12.7, 18.2 and 19.0 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 5; b) Crystalline Form II of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 8.7, 15.7, 17.2, 19.4 and 20.0 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 6; c) Crystalline Form III of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 8.2, 9.1, 12.3, 15.0 and 17.6 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 7; d) Crystalline Form IV of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 13.6, 18.3, 19.5, 21.9 and 24.3 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 8; e) Crystalline Form V of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 3.6, 7.6, 14.1, 17.8 and 19.5 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 9 and f) Crystalline Form VI of nilotinib L-tartrate, characterized by data selected from: an X-ray powder diffraction pattern having peaks at 4.7, 12.1, 16.3, 21.0 and 24.4 degrees two theta ± 0.2 degrees two theta or an X-ray powder diffraction pattern substantially as depicted in Figure 10.