Objective To prepared 125I-103Pd hybrid radioactive seeds and to explore their therapeutic effect on pulmonary carcinomas.nethods The 125I-103Pd hybrid radioactive seeds were prepared by a chemical method of step-by-step coat plating.Pulmonary adenocarcinoma of GLC-82 cells and pulmonary large cell carcinoma of H460 cells were cultured in vitro and then were exposed directly to125I,103pd and125I103pd seeds for 48 hours to observe the killing effects of radiation.GLC-82 and H460 tumor models were established and 20 mice chosen randomly for each model.For each tumor model.there were 4 groups(n=5 each).Then 125I-103pd,125I,103Pd and nonradioactive seeds were implanted into the tumors.Tumor sizes and weights of mice were measured and recorded every 5 days for a 2-month observation.Resuits The125I-103Pd hybrid radioactive seeds were prepared successfully.After a 48-hour radiation from radioactive seeds, the GLC-82 cells within one particulate around 125I,103Pd or1 25I_103Pd seeds were inhibited so as to become swollen and transfiguring.The H460 cells around125I seeds showed no obvious abnormality while those within one Darticalate around 103Pd or125I-103pd seeds were much fewer. No mouse died during the observation period.The radioactive seeds could inhibit the tumors.The radiotherapeutie effects were similar in two tumor modes:125I_103Pd seeds>103Pd seeds≈125I seeds>non-radioactive seeds.H460 tumors grew much faster than GLC-82 tumors.Meanwhile the seeds with the same nuclide were much more effective for GLC-82 tumors than for H460 tumors.Conclusion TheI_l03pd hybrid radioactive seeds are clinically applieable due to their effective inhibitions of tumor growth.