In BCRL (breast cancer-related lymphoedema), arm swelling is unevenly distributed and some regions are partly or entirely spared. In particular, the hand may or not be swollen, but when involved functional impairment can be substantial. We have found previously that, when the ipsilateral hand is spared of swelling (in a limb with swelling proximal to the hand), the local lymph drainage rate constant (k) is at least as high as in the contralateral hand, contrary to the traditional ‘stopcock’ concept of reduced lymph drainage from the whole limb. In the light of this finding, we have investigated lymph drainage in the hands of eight women with BCRL and moderate-to-severe hand swelling, using γ-camera quantitative lymphoscintigraphy. Images showed pronounced superficial activity in the ipsilateral swollen arms of most patients, indicating dermal backflow. k for ^99mTc-labelled hIgG (human IgG) measured over 5 h in the subcutis of the ipsilateral swollen hand was 34±24% less than in the contralateral hand (P=0.013). Activity measured in the ipsilateral swollen forearm increased progressively, but there was very little increase in the contralateral forearm, indicating retention of ^99mTc-labelled hIgG in the swollen forearm. It is concluded that lymphatic function in the swollen hand is impaired, and that there appears to be two populations of women with BCRL, i.e. spared-hand and swollen-hand, irrespective of the cancer treatment received.