Patients' illness representations and beliefs about treatment for depression and anxiety, as well as their perceived needs, are important for treatment. A systematic review was conducted of 71 studies describing the beliefs or perceived needs of patients and non-patients. Patients give multi-dimensional explanations for depression and see both psychological and medication treatment as helpful. People who suffer from depression have more positive beliefs about biological etiology and medication treatment than healthy people, or those with less severe depressive symptoms. Anxiety patients view psychological interventions as their best treatment option. Between 49% and 84% of the patients with depression or anxiety perceive a need for treatment, mostly for counseling and medication. All patients prefer psychological treatment forms to medication. A majority of patients view antidepressants as addictive and many perceive stigma and see practical and economic barriers to care. The most vulnerable groups in terms of seeking and receiving mental health care for depression and anxiety seem to be minority groups, as well as younger and older patients. More research is required into the specific needs of anxiety and depression patients. Open communication between patient and provider could lead to valuable improvements in treatment.