Low total lymphocyte count (TLC) has been found to be a poor prognostic factor in adults affected by heart diseases, malignancy, and renal failure. The aims of this study were to verify if a low TLC was associated with in-hospital mortality in older persons and to evaluate whether this association was independent of the presence of multiple co-existing diseases (multimorbidity).The authors carried out a cross-section analysis of data of 65+ years old patients (n=596) admitted to a Geriatric Unit in Northern Italy. TLC, total white blood cell count (WBC) and serum albumin were assayed the day after admission. The presence and severity of diseases were evaluated with the Geriatric Index of Comorbidity (GIC). Other covariates included age, gender, cigarette smoking, cognition (Mini-Mental State Examination) and function (Activities of Daily Living). Logistic regression models were created to study factors affecting in-hospital death.TLC was inversely correlated with both age and multimorbidity. Patients in the lowest tertile of TLC had the highest association with death during hospitalization (OR 6.1, 95% CI 1.1-33.6) independently of multimorbidity and all the other covariates. Stratifying the sample by degree of multimorbidity, this association was clearest in patients with the least severe multimorbidity (GIC