Background: The elderly population is the thoroughly affected by new cases of cancer, as well as by its complications. The occurrence of early death (in the first six months after diagnosis) is one of the most important outcomes to be studied in this population. This study aims to identify if simple baseline laboratory tests can be used as predictive factors for early death in older cancer patients. Methods: Prospective cohort enrolled elderly patients ≥ 60 years with a recent cancer diagnosis admitted between 2015 -2017. Sociodemographic, tumor-related and laboratorial (leukocytes, creatinine, platelets and hemoglobin) variables were collected at admission and analyzed. Survival analysis (Kaplan-Meier) and Cox proportional hazard regression was performed. The outcome was a six-month death. Descriptive, univariate and multivariate analysis of Cox proportional hazards and Kaplan-Meier global survival were performed. Results: A total of 746 patients with an average of 71 (± 7.4) years were eligible. 16.5% died in the first six months after diagnosis. Risk factors for early death were controlled by age. Leukocytes < 4,000 / mm3 or > 12,000 / mm3 (HR 2.51 IC95% 1.68-3.75), Creatinine > 1.7mg / dL (HR 2.14 95% CI 1.37-3.36), Platelets < 150,000 / mm3 or > 300,000 / mm3 (HR 1.92 CI 95% 1.31-2.80) and Hemoglobin < 12 g / dL if female, or < 13 g / dL, if male (HR 1.89 95% CI 1.27-2.83) were all associated with greater risk of dying in the first six months after diagnosis (log rank < 0.001). Conclusions: Baseline laboratory tests performed at the hospital admission of the elderly cancer patient may be a simple way to help the clinician to identify patients at higher risk of early death.