Patients with cirrhosis often develop malnutrition and micronutrient deficiencies, leading to a worse prognosis and increased mortality. Our main goal was to assess the prevalence of micronutrient deficiencies in patients with decompensated cirrhosis. This was a prospective single-center study including 125 consecutive patients hospitalized for acute decompensation of cirrhosis (mostly of alcoholic etiology). A blood test including trace elements and vitamins was performed on admission. The main micronutrient deficiencies observed were vitamin D (in 94.5%), vitamin A (93.5%), vitamin B6 (60.8%) and zinc (85.6%). Patients in Child-Pugh class C had lower levels of vitamin A (p < 0.0001), vitamin E (p = 0.01) and zinc (p < 0.001), and higher levels of ferritin (p = 0.002) and vitamin B12 (p < 0.001) than those in Child-Pugh class A and B. Patients with a higher model of end-stage liver disease (MELD) score had lower levels of vitamin A (p < 0.0001), vitamin E (p < 0.001), magnesium (p = 0.01) and zinc (p = 0.001), and higher levels of ferritin (p = 0.002) and vitamin B12 (p < 0.0001). Severe hepatic insufficiency correlated with lower levels of zinc, vitamin E and vitamin A, and higher levels of vitamin B12 and ferritin.