The research sought to determine whether males who harm themselves are younger than those who did not and to determine whether the legal category of the individuals distinguished the frequency of deliberate self-harm. The data came from nursing daily ward report books on 4 wads over a 30-month period. Results revealed 122 incidents of deliberate self-harm. Five individuals (4 percent of the participants) were involved in 82 incidents (67 percent of the total). The individuals who engaged in deliberate self-harm were significantly younger than those who did not, regardless of classification under the Mental Health Act of 1983 and regardless of whether they had only mental illness or only psychopathic disorder. The period of time since admission to the hospital was shorter for those who engaged in deliberate self-harm than for those who did not, but not to a significant extent. The frequency of deliberate self-harm was similar among individuals with psychopathic disorders and those with mental illness. Tables and 15 references (Author abstract modified)