Background: In this study, we aimed to analyze the underlying diseases, laboratory findings and clinical outcomes of elderly patients infected with COVID-19. We also investigated the value of laboratory parameters in the estimation of critical cases and mortality in elderly patients. Materials and Methods: The study included 314 elderly patients aged 60 years and older who were diagnosed with COVID-19.The patients were divided into two groups according to age, as young old patients (60-74 years) and old old patients (≥75 years). Participants' age, gender, underlying diseases, laboratory findings, disease severity and survival data were obtained from hospital records. Results: The most common comorbidities in elderly patients were hypertension (57.6%), diabetes mellitus (33.8%) and cardiovascular disease (28%). Old old patients had higher rates of critical type (63.4% vs 30.8%, P<0.001) and death (41.9% vs 21.3%, P<0.001) compared to young old patients. The leukocyte count, neutrophil count, urea, creatinine, C-reactive protein (CRP), procalcitonin, ferritin, troponin T, creatine kinase-MB, prothrombin time and D-dimer values were higher in the old old group compared to the young old group. In contrast, hemoglobin and albumin values were lower in the old old group. The areas under the curve (AUC) of albumin, CRP, procalcitonin, ferritin, troponin T and prothrombin time were greater than 0.80 to predict critically elderly COVID-19 patients. Ferritin had the highest AUC for predicting death (AUC: 0.819) followed by CRP (AUC: 0.805) and procalcitonin (AUC: 0.796). Conclusions: We found higher rates of critical type and death in old old patients compared to young old patients. In addition, ferritin, CRP, and procalcitonin were strong predictors of both disease severity and mortality in COVID-19-infected elderly subjects.