Mental healthcare services need to be sensitive towards the cultural needs of patients. Cross‐cultural opening is an organizational process to fulfil these needs. This study aims to provide representative structural and procedural data regarding the use of German outpatient mental healthcare services by allochthonous patients, the diversity of psychotherapists in outpatient mental healthcare service, the cross‐cultural encounters of therapists and the cross‐cultural sensitivity of psychotherapists working in this healthcare area. Of all public outpatient psychotherapists in Hamburg, 81% (n = 485) participated in this survey. Regarding the distribution of the population in this metropolis, allochthonous therapists were underrepresented. Unlike the overall distribution of foreign inhabitants, the largest groups of immigrant therapists came from England, German‐speaking countries and other countries within the European Union. The proportion of allochthonous patients in outpatient mental healthcare service was almost half of the proportion of the allochthonous in the general population. Psychotherapists with a migration background regarded themselves as having a higher level of cross‐cultural sensitivity than their native colleagues, especially those who have had fewer cross‐cultural encounters. Overall, psychotherapists named different challenges in providing cross‐cultural treatment. For the German outpatient mental healthcare service to be more accessible to immigrants and their descendants, a greater number of bilingual psychotherapists must gain access to the mental healthcare service, and more advanced cross‐cultural sensitivity training and supervision should be provided. Copyright © 2012 John Wiley & Sons, Ltd. Key Practitioner Message German outpatient psychotherapists are culturally and linguistically diverse. Nevertheless, psychotherapists with a migration background are underrepresented in outpatient mental healthcare services. Patients with a migration background are also underrepresented in the German outpatient mental healthcare system. Because mental healthcare services must be sensitive and respectful towards patients' cultural and linguistic needs, the mental healthcare outpatient service must be more accessible to therapists who speak languages other than German and English. Psychotherapeutic treatment of patients with a migration background can be tremendously challenging because of other cultures' differing value systems. Prospective, advanced training in cross‐cultural sensitivity and cross‐cultural supervision should be provided.