Background:Malnutrition in hospitalized adults is a highly prevalent problem. Thernworldwide prevalence of malnutrition in hospitals ranges from 15â€“54%. Hospitalrnmalnutrition is associated with delays in recovering from illness, increased cost of care,rncomplications, increased the length of stay, mortality and poor quality of life compared tornwell-nourished patients. In hospitals, length of stay (LOS) is a priority concern but it may bernprolonged by malnutrition through its effect on immune functions, wound healing processrnand greater risk of complications. Amidst the high rates of malnutrition documentedrnworldwide and its associated consequences, little is known on clinical adverse outcomes likernprolonged length of hospital stay in the Ethiopian hospital setting rnObjective:The study aimedto evaluate the effect of malnutrition at the time of admission onrnthe length of hospital stay among adult patients in TikurAnbessa Specialized Hospital, rnEthiopia rnMethod:A prospective cohort study was conducted among hospitalized adult patients, whornwere admitted to Tikur Anbessa specialized hospital medical or surgical wards ,with arnminimum length of stay of 24 hours were recruited. Proportional allocation and Consecutivernsampling method were used to select patients. At admission, Patients Nutritional statuswerernassessed within 48 h using the Subjective Global Assessment (SGA).The main clinicalrnoutcome Length of stay in hospital (LOS) was captured for every patient in days. Sociorndemographic, economic and admission related Patient clinical Characteristics were includedrn.Data were compiled, checked, coded ,entered and cleaned using Epi Data 4.4.1 and allrnstatistical tests were done using STAT version 15.1 software. Descriptive statistical tests andrnmultivariate Coxâ€™s regression model was used to investigate the effect of malnutrition on thernlength of hospital stay after adjusted for several potential nutritional and clinical confoundersrnrecorded at admission. Results are expressed as hazard ratios (HR) and their 95% CI.rnrnResult: On admission a total of 417 patients , predominantly male (54.2%), were included.rnThe mean age was 38 Â± 16 years. Using Subjective Global Assessment (SGA), the magnitudernof malnutrition was 62.1%(95% CI: 57.3%, 66.6%) . The mean length of stay was 13.84 daysrnÂ± 7.53SD, with a significant difference (p