AIM: The objective of this study was to describe patients who experienced an out-of-hospital cardiac arrest (OHCA) by age group. METHODS: All patients who suffered from an OHCA between 1990 and 2005 and are included in the Swedish Cardiac Arrest Registry (n = 40,503) were classified into the following age groups: neonates, younger than 1 year; young children, between 1 and 4 years; older children, between 5 and 12 years; adolescents, between 13 and 17 years; young adults, between 18 and 35 years; adults not retired, between 36 and 64 years; adults retired, between 65 and 79 years; and older adults, 80 years or older. RESULTS: Ventricular fibrillation was lowest in young children (3%) and highest in adults (35%). Survival to 1 month was lowest in neonates (2.6%) and highest in older children (7.8%). Children (<18 years), young adults (18-35 years), and adults (>35 years) survived to 1 month 24.5%, 21.2%, and 13.6% of cases, respectively (P = .0003 for trend) when found in a shockable rhythm. The corresponding figures for nonshockable rhythms were 3.8%, 3.2%, and 1.6%, respectively (P < .0001 for trend). CONCLUSIONS: There is a large variability in characteristics and outcome among patients in various age groups who experienced an OHCA. Among the large age groups, there was a successive decline in survival with increasing age in shockable and nonshockable rhythms.