The article presents an analysis of complicated course of influenza A(H1N1) in a female patient undergoing treat- ment in the intensive care unit. Basic clinical and bio- chemical blood parameters are investigated in dynamics, the estimation of indexes of arterial blood gas structure before and during the respiratory support is given. The dynamics of ultrasound and radiographic studies results is described. The principal directions of drug treatment and specifics of artificial lung ventilation are shown, the data of pathoanatomical study are presented.