H1N1 influenza virus infections in immunosuppressive patients cause complications. Clinical and laboratory findings of H1N1 positive haematology patients were evaluated in this study. Materials and methods: The "H1N1 Swine Influenza Suspicious Case Notification Form and Inpatient Follow-up Form" was prepared for 15 patients with suspected H1N1 infection between October 2009 and May 2010. H1N1 was detected by real-time RT-PCR assay. For all cases medical records were reviewed for clinical, demographic, and haematologic information. Results: H1N1 positivity was confirmed using real-time RT-PCR in 9 out of 15 patients (11 men, 4 women). One of the 9 patients had been followed up due to aplastic anaemia, 1 due to Evans syndrome, and the remaining 7 due to haematologic malignancy. Among the 9 patients diagnosed with H1N1, 3 had previously undergone autologous haemopoietic stem cell transplantation (HSCT). H1N1 was detected in HSCT recipients in the early post-transplant period (range 7-21 days). The most prominent symptoms were as follows: high fever, cough, vomiting, nausea, and diarrhoea, in descending order. Oseltamivir was given to all patients. Eight patients responded to the treatment and recovered clinically. One patient (57-year-old female with multiple myeloma), required intensive care and she died due to severe sepsis and pneumonia. Conclusion: Our data show that subjective findings like headache and fatigue often seen in influenza infections were not the dominant clinical presentation in these patients. These infections should be considered in patients with haematological malignancy, and appropriate treatment and prophylaxis should be started early.

H1N1 influenza virus infections in immunosuppressive patients cause complications. Clinical and laboratory findings of H1N1 positive haematology patients were evaluated in this study. Materials and methods: The "H1N1 Swine Influenza Suspicious Case Notification Form and Inpatient Follow-up Form" was prepared for 15 patients with suspected H1N1 infection between October 2009 and May 2010. H1N1 was detected by real-time RT-PCR assay. For all cases medical records were reviewed for clinical, demographic, and haematologic information. Results: H1N1 positivity was confirmed using real-time RT-PCR in 9 out of 15 patients (11 men, 4 women). One of the 9 patients had been followed up due to aplastic anaemia, 1 due to Evans syndrome, and the remaining 7 due to haematologic malignancy. Among the 9 patients diagnosed with H1N1, 3 had previously undergone autologous haemopoietic stem cell transplantation (HSCT). H1N1 was detected in HSCT recipients in the early post-transplant period (range 7-21 days). The most prominent symptoms were as follows: high fever, cough, vomiting, nausea, and diarrhoea, in descending order. Oseltamivir was given to all patients. Eight patients responded to the treatment and recovered clinically. One patient (57-year-old female with multiple myeloma), required intensive care and she died due to severe sepsis and pneumonia. Conclusion: Our data show that subjective findings like headache and fatigue often seen in influenza infections were not the dominant clinical presentation in these patients. These infections should be considered in patients with haematological malignancy, and appropriate treatment and prophylaxis should be started early.