The aim of this study was to calculate the number and costs of hospital bed-days due to alcohol use in Ireland over the five year period 2000 to 2004. Age and sex specific Irish alcohol-attributable-fractions (AAFs) were developed by combining international risk estimates with Irish consumption data where available; where not available international AAFs were used. These were applied to national datasets to count the number and costs of bed-days wholly caused and prevented by alcohol and that proportion of bed-days that were partially caused and prevented by alcohol. Between 2000 and 2004, alcohol was estimated to have caused 3,428,973 (10.3%) and prevented 529,239 (1.6%) of hospital bed-days, giving a net number of bed-days due to alcohol of 2,899,734 (8.7%). Over this period the hospital inpatient costs attributed to the negative effects of alcohol were 953,126,381 euros, the costs attributed to hospitalisations prevented were 147,968,164 euros; giving net costs of alcohol-attributed bed-days of 805,158,217 euros. Chronic conditions accounted for 3,262,408 (95%) hospital bed-days due to the harmful effects of alcohol. Conditions not wholly due to alcohol accounted for 2,297,412 (67%) hospital bed-days due to the harmful effects of alcohol. The negative impacts of alcohol were greater than previously thought and spread across the whole population.