Abstract: A fluorogenic compound comprising a biologically active component and a hypoxia-activated protecting group which is fluorogenic. The biologically active component is bound to the fluorogenic component at an active binding position such that activity of the biologically active compound is suppressed until the protecting group is released. The protecting group is cleaved under hypoxic conditions, releasing the active compound and a fluorescent compound. The compounds can therefore be used in the treatment of hypoxia-related disease and disorder, such as tumour, and enable imaging of the release of the biologically active compound.