We hypothesized that severity of human non-typhoid Salmonella (NTS) infection was a marker of 0-30 and 31-365-d mortality. All patients with first-time detection of NTS in stool specimens in North Jutland County, Denmark, 1995-2003, were categorized into 4 groups. Group 1 was not hospitalized in relation to their NTS infection, group 2 was hospitalized without sampling of blood cultures, group 3 was hospitalized with blood cultures obtained in which pathogenic micro-organisms were not detected, and group 4 had blood culture-proven bacteraemia. Among 1764 NTS patients, 2 of 1082 (0.2%) in group 1, 14 of 344 (4.1%) in group 2, 20 of 248 (8.1%) in group 3, and 19 of 90 (21.1%) in group 4 died within 365 d. Using group 2 as reference, age and comorbidity adjusted 0-30-d mortality rate ratios (MRR) with 95% confidence intervals (CI) could not be computed for group 1 (no deaths), while they were 1.8 (0.6-5.5) for group 3 and 1.4 (0.4-4.9) for group 4. For the 31-365-d period, MRR (95% CI) were 0.16 (0.03-0.8), 1.6 (0.7-3.7), and 2.5 (1.1-5.8), respectively, for the 3 groups. Severity of NTS infection was an age- and comorbidity-independent short- and long-term prognostic marker of mortality.