We have investigated the clinical efficacy for the detection of bone metastases of two recently marketed bone-seeking radiopharmaceuticals, HDP and DPD, compared with traditionally used MDP. Twenty patients received 15 mCi 99mTc-MDP; after assessment ten of these patients later received 15 mCi 99mTc-DPD and ten other patients of this group were injected with 15 mCi 99mTc-HDP. Scintigraphy took place 3 h after tracer injection. Quantitative analysis included the calculation of normal bone to soft tissue ratios, lesion to soft tissue ratios and lesion to normal bone ratios for all three radiopharmaceuticals. Visual inspection of the scintiphotos revealed the same number of bone lesions at the same localisations. Statistical evaluation of our quantitative data showed that the lesion to normal bone ratio was significantly higher for MDP than for DPD. No further significant differences in the uptake in normal bone or in the metastatic lesions were found between all three radiopharmaceuticals. It is concluded that the new bone-seeking agents DPD and HDP do not possess clinical advantages over MDP for the detection of skeletal metastases.