During the past decades the Western countries have paid attention to their Mental Health legislation, in particular, by making changes concerning involuntary treatment. In Western countries legislation allows involuntary treatment of the mentally ill. Involuntary psychiatric treatment is motivated by either potential harm to others (for the good of society) or by need for treatment and/or potential self-harm (for the good of the patient). The aims of this study were to describe to what extent the danger to others criterion is used as a motivation for involuntary hospitalization and detainment in Finland, and to what kind of patients this criterion is applied. The study involves a retrospective chart review of all the treatment periods of a six month admission sample in three Finnish university hospitals. We found that potential harm to others has been rarely used as a motivation for involuntary referral or detainment together with other motivations, and virtually never as the sole motivation. With the exception of gender, which was most often male, patients with potential harm to others did not differ significantly from other involuntarily treated patients. Coercion (defined as seclusion, the use of restraints, forced medication, physical restraint or restrictions in leaving the ward) was not used with these patients more regularly than with the patients motivated by the other criteria. Length of stay (LOS) in a psychiatric hospital did not differ between the patients determined harmful to others and the other involuntarily treated patients.