Objectives: To evaluate sensitivity and specificity of HI and CF tests for detecting antibody responses following naturally occurring influenza A and B infections. Methods: One hundred and twenty blood samples were drawn from one hundred patients with flue-like illness and twenty apparently healthy control subjects and tested at Central Health Laboratory in Baghdad/ Iraq using HI and CF tests for detecting three currently circulating influenza A and B strains during the period from the 1^st of January 2008 to the 1^st of June 2009.                                                  Results: 78-80% of the patients with flu-like illness responded to a t least one of three influenza virus antigens as measured by HI, while 34-35% of those patients showed a response by CF test. Conclusions: HI test has a higher sensitivity and lower specificity than CF test for detecting antibody responses from patients with influenza A and B viral infections.