Objective: To observe the possibility of neoplasm needle track implantation after radioactive seeds implantation and seek preventive measures to avoid it. Methods: Superficial tissue of 250 seeding needle cores and 250 stylophores employed in neoplasm radioactive seeds implantation was smeared on slides to search for tumor cells. All patients received chemotherapy or endocrine therapy after operations. Ultrasound B-mode or computer tomography (CT) was performed at 10th day, 30th day, 60th day, and 180th day post operation to detect neoplasm implantation metastasis through needle tracks.Results: Positive cells were found on 13 of 250 (5.20%) cores, and 7 of 250 (2.80%) stylophores. The difference was not statistically significant (P ＞ 0.05). The positive cells frequency of needles those traversed distance less than 3 cm in normal tissue was 6.19% (13/210), while the frequency of the others those traversed longer distance in normal tissue was 2.41% (7/290).The positive cells frequency of needles traversing different distances in normal tissues is significantly different (P ＜ 0.05). No neoplasm was detected through needle tracks by ultrasound B-mode or CT in 180 days after operation. Conclusion: Tumor cells could ablate into the needle track during radioactive seed implantation. Some preventive measures, such as optimization of pre-operation and intra-operation treatment plan, chemotherapy or endocrine therapy after operation, may be beneficial to avoid the implantation metastasis of neoplasm in seeding needle tracks.