Cerebral cavernous malformations (CCMs) are congenital abnormalities of the cerebral vessels. The de novo development of new lesions in this disease has been reported. However, the underlying mechanism of progressive CCMs in such patients remains unclear. This report documents two cases of multiple probable CCMs that showed a progressive behaviour. The plasma levels of vascular endothelial growth factor (VEGF), and transforming growth factor-β1 (TGF-β1) were measured using an enzyme-linked immunosorbent assay (ELISA). The concentration of both VEGF and TGF-β1 in plasma was increased in these patients. A relationship was observed between high concentrations of growth factors and progressive CCMs. Even though a causal linkage between these conditions cannot be confirmed, a continuous high VEGF level in plasma could be a possible clinical indicator for subsequent intracerebral haemorrhages in the CCM patients.