Intensivists often refuse admission to cancer patients needing critical care, which may result in denial of effective care for some deserving patients. A cancer patient may need admission to intensive care units for a variety of reasons. The outcomes of patients with hematological malignancies, previously dismal, have improved over last 10 years. The previously known indicators of poor outcome are no longer valid in view of recent advances in intensive care. A select group of patients with hematological malignancies may be offered aggressive therapy for a limited duration and then prognosis can be reassessed. Cancer chemotherapy can produce toxicities affecting all major organ systems. Such patients may be admitted with acute organ dysfunction or years afterwards for incidental illnesses. Knowledge of these toxicities is essential for early diagnosis, management and prognostication in such patients. The post-surgical cancer patient has unique problems, the problems of these groups are discussed. The post-surgical cancer patient may need care ranging from only monitoring; in view of supra-major surgery in some patients; to fully aggressive intensive care for post-surgical anastomotic dehiscence, mediastinitis, septic shock and multiorgan dysfunction in others. The metabolic and mechanical complications commonly seen in non-surgical cancer patients are also discussed. Intensive care should be offered to all cancer patients who have a reasonable chance of cure or palliation of their disease.