The current paradigm is that untreated lung cancer is invariably and rapidly fatal, therefore the medical community normally dismisses the idea that a patient could live with such a disease for years without any therapy. Yet evidence from lung cancer screening research and from recent clinical series suggests that, although rarely recognised in routine practice, slow-growing lung cancers do exist and are more common than previously thought. Here, current evidence is reviewed and clinical cases are illustrated to show that slow-growing lung cancer is a real clinical entity, and the reasons why management protocols developed in the screening setting may also be useful in clinical practice are discussed. Features suggesting that a lung cancer may be slow-growing are described and appraised, areas of uncertainty are examined, modern management options for early-stage disease are evaluated and the influence that all this knowledge might have on our clinical decision-making is weighed. Further research directed at developing appropriate guidelines for these peculiar but increasingly common patients is warranted.