A diagnosis of idiopathic pulmonary fibrosis (IPF) has serious implications for the affected individuals, who have a 50% likelihood of dying within 2-3 yrs, an outcome which is worse than many cancers. A swift and accurate diagnosis is imperative, especially as commencing treatment at a relatively early disease stage may have the greatest impact on reducing disease progression. The 2011, IPF guidelines provide updated and simplified IPF diagnostic criteria that may facilitate making a more confident diagnosis. The key investigational tool is high-resolution computed tomography (HRCT). In the presence of the four classical features, that together accurately identify a usual interstitial pneumonia (UIP) pattern, a definitive diagnosis of IPF can be made. When HRCT honeycombing is absent, even in the presence of all other features including traction bronchiectasis, the guidelines provide no designation for this constellation of features that many clinicians and radiologists would regard as consistent with UIP. The diagnostic algorithm suggested by the 2011 guidelines emphasises the importance of multidisciplinary discussion between clinicians, radiologists and pathologists to improve diagnostic confidence. The course of disease in IPF is unpredictable, but the importance of an early diagnosis is clear, as individuals with less severe lung function abnormalities have a better prognosis.