In order to explore the status quo of the assessment of nursing care needs in newly admitted inpatients on oncology wards a survey in a German university hospital was carried out. Research questions included: Do the nurses collect data regarding nursing care needs of admitted cancer patients? When are the data collected? What data are collected? What is documented, when is it documented, and is the patient involved in the documentation? What, if any, factors on the part of nurses have an impact on the way in which these data are collected? Two methods were used to collect research data: nursing documents of hospitalised cancer patients were analysed (n = 68), followed by an interview with the nurses (n = 81). Beforehand, an instrument was developed and tested for both investigative methods. The main result was: the nurses' perception of the needs' assessment was incongruent with data in the patients' documentation files. The study showed that nurses consider their documentation of nursing care needs to be more comprehensive with regard to the time and content/areas of documentation than it actually is. With regard to the psychological, social, and spiritual care needs, for example, this means: in the nurses' own opinion, they had taken into account these needs far more strongly than they actually had. According to the analysis of the care documents, patients were involved in the documentation in 15% of the cases. According to the nurses, general communication skills, the use of assessment instruments, and the standardisation of the documentation need to be improved. The review of international literature confirms the deficiency recorded by this survey. The oncology patients' perspective should be included more strongly in the assessment of nursing care needs. In this way, individual nursing care needs are assumed to be understood more appropriately. Self-assessment instruments could be a suitable resource in this context. The instruments have to be introduced by education, and their validity, reliability, practical relevancy, and applicability need to be checked continuously.