Background: Proliferation of non-falciparum species of plasmodium into predominant falciparum populations compromises the utility of monobiomaker based malaria Rapid Diagnostic Test (mRDT). This study evaluated the validity of a mono-biomarker based Carestart®) and Paracheck™ mRDTs in use at a Military Medical Centre in Ghana. Methodology: The study was designed to assess the validity of named mRDTs in a setting in Ghana. Blood samples collected from a consecutive series of 207 febrile patients in the months of June and July 2020, were tested for malaria parasites, using the mRDTs and microscopy as the gold standard. Prevalence, validity, and reliability metrics were determined using Frequentist, Receiver Operating Characteristics (ROC), and Kappa statistics, respectively. Results: The prevalence was 23.2% and 12.3% using microscopy and candidate mRDT, respectively. Sensitivities and specificities were 53.2% and 98.1% (Carestart®), 45.8% and 99.4% (Paracheck), respectively. Neither ROC analysis showed a significant disparity between mRDTs (Carestart®: AUROC=0.75 vs Paracheck™: AUROC=0.73), nor the reliability index showed disagreement between both mRDTs (Cronbach’s α = 0.92). But there was significant disagreement between microscopy and mRDTs (Carestart®: Kappa=0.58 vs Paracheck™: Kappa=0.55). Conclusion: The use of a monobiomaker mRDTs in this study led to a significant variation between the ‘internal’ and ‘ecological’ validity metrics. Averagely, 84% mRDT false negatives was non-falciparum. It is therefore, critical to accelerate the implementation of WHO’s recommendation to switch from mono to multiple biomarker (s)-based mRDTs for detecting both falciparum and non-falciparum species. Extended research is needed to consolidate our understanding of the dynamics of malaria among our military personnel exposed to non-falciparum plasmodium.