[en] Radioimmunoimaging characteristics of a new monoclonal antibody EBA-1 and its F(ab')₂ fragments utilizing nu/nu mice bearing human breast carcinoma xenografts are described. ¹¹¹In-DPTA conjugates of EBA-1 localized with tumor/blood ratios of 0.99 ± 0.10 (P < 0.3) and 4.65 ± 1.60 (P < 0.05), and localization indices of 1.25 and 2.61 at 24 and 72 h, respectively. A tumor/blood ratio as high as 28.86 ±6.90 (P < 0.025) was obtained with EBA-1 F(ab')₂ radioconjugates at 48 h. These results suggest that EBA-1 and its F(ab')₂ might be useful reagents in radioimmunoimaging and radioimmunotherapy. (author)