Although the neurotoxicity of many anticancer therapies is well documented, the impact of cancer treatment on cognitive functioning has been studied less frequently. The present study examines deficits in cognitive functioning and their correlation with medical data as well as with psychosocial variables. A standardised neuropsychological test battery and several questionnaires were administered to a random sample of 119 patients. 24% of our patients fulfilled our criterion for cognitive impairment. There were no significant associations between the results of the neuropsychological testing and the current affective status or self-reports of attentional deficits in daily life. Cognitive impairment occurs in a clinically relevant percentage of cancer patients and cannot be explained exclusively due to depression or anxiety. Since subjective and objective cognitive impairment data showed little correlation, neuropsychological evaluation should not only be based on subjectively-reported complaints, but also on objective measurements.