The cerbB2 oncogene antisense oligodeoxynucleotide probe was obtained by chemical crosslinking approach. Its T2 relaxivity was 0.156×106 mo l－1·s－1 , which was determined with a 1.5T MR system. The saturated magnetization, specific saturated magnetization, specific retentivity and retentivity were 69.423 8emu/g Fe, 68.413 4e mu/g, 30.354 1e mu/g and 19.734 5 Gs, respectively. These measurements were obtained with a vibratingsample magnetometer. To test its effectiveness, highly expressive SKBr3 oncocytes were transfected with the antisense oligodeoxynucleotide probe. Meanwhile, SKBr3 oncocytes were transfected with the sense and nonsense oligodeoxynucleotide probe, and normal mouse liver cells were transfected with the antisense oligodeoxynucleotide probe. The results show that the antisense probe could enter the SKBr3 oncocytes effectively, and improve the magnetic properties and decrease the signal intensity in MR scanning obviously.