Tumour is a morbid state, characterized by spontaneous outgrowth of an abnormal mass of cells. The evolution of tumours is random, disorganized, a condition of numerous mutations. The properties are biased and incompletely comprehended. It is a malignant or benign condition that encompasses its own rules of morphogenesis, an immortal state that elucidates different physiology. It is a pathological crisis that still haunts the minds of scientists, physicians and patients, a complete cure of which is still a dream to be realized. The unpredictable microenvironment of cancerous cells in all of its existing forms i.e. leukaemic cells, solid tumours and sarcomas is well documented. This phenomenon expressed by cancerous sites in the body poses various obstacles towards drug efficacy. Thus, it has become necessary to address briefly the issues relating to tumour physiology, its vasculature and angiogenesis. The information could provide insight towards the development of tumour-targeted drug delivery. The salient features regarding these have been discussed.