Background: Lower Respiratory Tract Infections (LRTIs) are a particular public health concern especially among sub-Saharan African countries. This is especially the case in Namibia where LRTIs are currently the third leading cause of death, 300 deaths in children under 5 years of age. To reduce the burden of Lower Respiratory Tract Infection (LRTIs) on health systems and ensure appropriate patient management, it is critical to know the most prevalent pathogens leading to LRTIs and their susceptibility patterns in the local setting. Consequently, the objective was to formulate cumulative antibiograms for ICUs of referral hospitals in Namibia to guide future antibiotic use. Methods: A retrospective analytical cross-sectional study was conducted over two years. The cumulative antibiograms were constructed in accordance with current guidelines. Results: 976 first isolate cultures were obtained from ICUs of the different referral hospitals. K. pneumoniae (8.8%, 8.1%) was a predominant pathogen in Windhoek Central hospital ICU in 2017 and 2018. In Oshakati intermediate hospital ICU, Enterobacter sp. (22.2%) and P. aeruginosa (37.5%) were the common pathogens in 2017 and 2018, respectively. A. baumannii isolates were > 90% susceptibility to colistin, carbapenems and tigecycline in 2017. In 2017, K. pneumoniae isolates were more susceptible to carbapenems (94% and 93.8% among isolates), amikacin (89.3%) and tigecycline (88.7%). In 2018, K. pneumoniae isolates were 100% susceptible amikacin, colistin and carbapenems. S. maltophilia isolates were more than 80% susceptible to all the tested antibiotics. S. aureus isolates were 100% susceptible to linezolid, rifampicin, teicoplanin, vancomycin in 2017 and in 2018. Its susceptibility to these antibiotics did not change. Conclusion: The susceptibility patterns of the common isolated gram-negative pathogens were highly variable. Meropenem in combination with gentamicin is now the recommended antibiotic combination for empiric therapy for patients with LRTIs in Windhoek Central Hospital ICU.