Background: Chlamydia pneumoniae (C. pneumoniae) is a respiratory pathogen associated with chronic inflammatory and its detection in human lung cancer suggests its involvement in cancerogenesis. Our study aimed to evaluate the association between C. pneumoniae infection and Lung Cancer disease in Moroccans patients and control cohorts, through a molecular investigation. Methods: The study comprised 42 lung cancer patients and 43 healthy controls. All participants provided demographics, Clinical, and Toxic behaviors datas, and a peripheral blood sample for testing, a Nested Polymerase Chain Reaction (PCR) was performed for C. pneumoniae Deoxyribonucleic acid (DNA) detection. Statistical analysis was performed using IBM ® SPSS ® software. Results: Positive Nested PCR results for cases and controls were respectively 33.3% and 4.7%, there by significant difference between cases and controls infection was identified (p <0.05). Data analysis also showed that tobacco could act synergically with C. pneumoniae infection as a risk factor of lung cancer. In fact a significant difference between patients and controls was shown for tobacco and alcohol use (p < 0.05). Conclusion: C. pneumoniae infection is potentially associated with primary Lung cancer in the Moroccan population and has combined effects with Tabaco consumption.