In many countries, psychiatric services have been reformed by reducing the size of hospitals and developing community mental-health services. We investigated this reform by assessing the relation between suicide risk and different ways of organising mental-health services. We did a nationwide comprehensive survey of Finnish adult mental-health service units between Sept 1, 2004, and March 31, 2005. From health-care or social-care officers of 428 municipalities, we asked for information, classified according to the European service mapping schedule, about adult mental-health services. For each municipality, we measured age-adjusted and sex-adjusted suicide risk, pooled between 2000 and 2004, and then adjusted for register-derived socioeconomic factors. A wide variety of outpatient services (relative risk [RR] 0·92, 95% CI 0·87–0·96), prominence of outpatient versus inpatient services (0·93, 0·89–0·97), and 24-h emergency services (0·84, 0·75–0·92) were associated with decreased death rates from suicide. However, after adjustment for socioeconomic factors, only the prominence of outpatient services was associated with low suicide rate (0·94, 0·90–0·98). We replicated this finding even after adjustment for organisational changes and inpatient treatment. Well-developed community mental-health services are associated with lower suicide rates than are services oriented towards inpatient treatment provision. These data are consistent with the idea that population mental health can be improved by use of multifaceted, community-based, specialised mental-health services. Academy of Finland.