HMD4, a human IgG (lambda) monoclonal antibody against ovarian carcinoma, was purified by affinity chromatography of CNBr-activated Sepharose 4 B coupled with goat antihuman IgG, 131I-HMD4 was prepared by chloramin-T or Iodogen method. The nude mice bearing human ovarian carcinoma (OSC-2) were intraperitoneally injected with 131I-HMD4, while 131I-labeled normal human IgG and normal murine IgG were used as controls. Imaging was performed daily using a gamma camera. For analysis of distribution and metabolism of 131I-HND4 in the nude mouse models, T/NT and T/B ratios were calculated. The HMD4 was specifically localized at the tumor masses in nude mice and the best imaging was obtained at 72 hours after injection. Total positive rate of imaging was 82%, while negative rate in the controls was 91%. Radioimmunoimaging index was highest (4.17) at 48 hours after injection. The average half life of 131I-HMD4 in the blood was about 30 hours.