Context & Objective: Lower respiratory tract infections (LRTIs) are prevalent diseases and a major cause of referral to primary healthcare centers. The present study aimed to identify the bacterial etiology of LRTIs to determine the trend changes within the past three decades and help ascertain the new scenarios of empirical LRTI therapy in Turkey. Data Sources: This systematic review was conducted by searching various electronic databases based on specified criteria. In total, 2,670 articles were identified, which had been published during 1990 - 2020 and could be potentially used, and 46 scientific studies that met the eligibility criteria were selected for the review. Results: The most frequently isolated bacteria in the reviewed studies were Acinetobacter spp. (31.68%), P. aeruginosa (16.59%), H. influenzae (14.30%), and S. pneumoniae (13.80%). Data analysis also indicated that the most frequent reports of LRTI agents were in Aegean region in Turkey during 2014-2020. Conclusions: This systematic review reflected the changes in LRTI agents over the past three decades in Turkey. Knowledge of the frequency of LRTI bacterial agents specific to each country could help healthcare professionals in reporting laboratory results and prescribing/selecting the most effective antibiotics for the treatment of the disease.