Introduction: Identifying and reporting nosocomial infections are at the center of attention of healthcare. The present study was carried out to study the problems of the National Nosocomial Infections Surveillance System (NNIS).

Methods: This mixed (Qualitative- Quantitative) descriptive study was performed in 2011. In the qualitative section, after a semi- structured interview, a questionnaire was designed and its validity was approved using experts’ opinion technique. The study population of the quantitative section included all hospitals in Tabriz and the samples consisted on 77 members of the hospitals’ Infection Control Committees, selected by means of 2-stage cluster sampling method. Qualitative data were analyzed using content analysis technique and Quantitative data were analyzed by descriptive statistical methods using SPSS 17 Software.

Results: The incidence of nosocomial infections reported according to the NNIS system was 0.56% showing low report of nosocomial infections which have resulted from lack of commitment of some physicians to documentation and reporting of nosocomial infection symptoms, lack of their active participation in Infection Control Committees, lack of appropriate validation system to identify problems, and lack of post-discharge follow up system for operated patients.

Conclusion: To solve the problems of National Nosocomial Infections Surveillance System and help produce accurate reporting of nosocomial infections, hospital infection control committee should play an active role by supporting senior management and greater participation of infection control practitioners. To solve the problems above, re-evaluation of the reporting process is recommended.