Background: Mental disorders can be associated with suicidal or aggressive ideation and behavior, especially in the context of embitterment. The aim of this study is to investigate the types, prevalence, and dangerousness of aggressive and suicidal ideations associated with embitterment. Methods: When therapists from the department of behavioral medicine detected signs of embitterment, aggression, or suicidal thoughts in their patients, they routinely filled out a questionnaire on aggressive ideation, assessed the embitterment, and contacted a senior psychiatrist. Additionally, patients answered an embitterment scale. Results: There were 127 patients (3.84% of all patients) with suicidal and/or aggressive ideation. They had an increased score of 2.93 (SD 0.74) on the embitterment scale, associated with personal vilification (62.7%), breach of trust (30.2%), public humiliation (25.4%), death/loss (5.6%), or attacks by another person (14.3%). We found that 83.5% of the patients harbored aggressive ideations; in 94.1% of this group, these were directed against the person who had caused the problem, 88.3% wanted to inflict severe damage, 38.8% to harm another person, 31.5% showed suicidal ideation, and 3.2% had fantasies of murder-suicide. Only 34.3% of the patients reported spontaneously about their current aggressive ideation. The limitations of the study are that the data come from an inpatient sample and patients were identified according to clinical judgement. Conclusion: Aggressive ideation is regularly associated with embitterment. This deserves the attention of therapists for the prevention of aggressive acts.