The complement system is composed of a network of proteins that play an important role in innate and adaptive immunity that range from opsonization of pathogens and chemoattraction to removal of apoptotic and necrotic cells. Activation of the system is exquisitely regulated, and inappropriate activation either due to deficiencies in key complement proteins or due to dysregulated activation has adverse consequences. There is also a growing appreciation that there is cross-talk between the complement system and other systems, especially the coagulation system (Kourtzelis et al. 2010) . For example, C5amediated tissue factor release from neutrophils has been implicated in the pathogenesis of thrombosis in patients on hemodialysis. Chest imaging features of patients afflicted with Influenza A (H1N1) in a Malaysian tertiary referral centre This is a retrospective descriptive study of the chest imaging findings of 118 patients with confirmed A(H1N1) in a tertiary referral centre. About 42% of the patients had positive initial chest radiographic (CXR) findings. The common findings were bi-basal air-space opacities and perihilar reticular and alveolar infiltrates. In select cases, high-resolution computed tomography (CT) imaging showed ground-glass change with some widespread reticular changes and atelectasis. In April 2009, a new global outbreak of a novel Influenza A virus, a swine virus with confirmed human infection, occurred. What is new about this virus is that it is unrelated to any swine influenza virus previously identified in North America. There is sustained humanto-human transmission in this new subtype of Influenza A virus [1] . It was termed Influenza A(H1N1) and 2009 H1N1 influenza by the United States Centre of Disease Control and Prevention (CDC) [2] and Pandemic H1N1/09 by the World Health Organization (WHO) [3] . The respiratory system is predominantly affected. Initial reported chest findings of A(H1N1) infections were bilateral diffuse lung opacities on chest radiographs (CXR). On computed tomography (CT), there were patchy ground glass opacities in both lungs with axial predominance and in the four lung quadrants consistent with acute respiratory distress syndrome [4] . To date, there has been no published data on CXR findings of patients with A(H1N1) in Malaysia. The authors report the CXR findings of 118 patients with confirmed A(H1N1).