Stem cell therapy has been demonstrated to be effective in the management of haematological malignancy and solid cancer, but its role in neurodegenerative conditions remains uncertain. We hypothesize that: (1) ventricular delivery of bone marrow stem cells improves functional outcome in experimental ischaemia of the mouse brain; and (2) this improved outcome is due to migration of bone marrow stem cells to areas of ischaemia. Twelve mice with transient cerebral hemisphere ischaemia were randomly allocated to receive bone marrow stem cells or saline. The six animals that underwent cell therapy were found to perform better and committed fewer errors in the water maze system compared with the six control mice. Migration of these bone marrow stem cells was evident within the ventricular cerebro-spinal fluid (CSF) system and the brain parenchyma. This could also occur in clusters of cells. Preferential migration of these cells took place in lesioned areas.