Abstract: Objective: To analyze the therapeutic efficacy of community acquired pneumonia（CAP） caused by atypical pathogens and bacteria,in order to guide the experimental therapeutic choice of antibiotics for CAP.Methods: Therapeutic efficacy was analyzed on 315 adult patients with CAP,of which the causative pathogens were identified at 12 centers in 7 Chinese cities from December 2003 to November 2004.Results: In 315 patients with CAP,the effective rate of therapy with β-lactam antibiotics was 90.3%;and that with β-lactam antibiotics plus macrolides or antibiotics containing floroquinilones was 95.7%.Treatment improvement in patients with atypical pathogen causes（mono-infection or mixed infection） showed no advantage of macrolides or floroquinolones over β-lactam antibiotics.In patients had comorbid illness with infection of mycoplasma pneumoniae and /or Chlamydia pneumoniae mixed bacteria,clinical outcome with therapy of β-lactam plus macrolides or floroquinolones was better than β-lactam antibiotics.Conclusion: Because high percentage of atypical pathogen in CAP in China,it is suggested to choose antibiotics active against atypical pathogen,especially for patients with comorbid illness or having modifying factors;therapies should involve in anti-atypical pathogens.