BACKGROUND:: Cognitive dysfunction experienced by individuals with cancer represents an important survivorship issue because of its potential to affect occupational, scholastic, and social activities. Whereas early efforts to characterize cognitive dysfunction primarily focused on the effects of chemotherapy, more recent evidence indicates that impairment may exist before systemic treatment. This study characterized cognitive dysfunction before adjuvant chemotherapy in a sample of men diagnosed with nonseminomatous germ cell tumors (NSGCT) of the testis. METHODS:: Men with newly diagnosed NSGCT were recruited after orchiectomy but before adjuvant chemotherapy. Patients completed neuropsychological tests to assess attention, learning, language, executive function, and motor function. Self-report measures of depression and anxiety were also administered. An overall cognitive function index was computed for participants. Cognitive impairment was defined as a z-score of less than or equal to -1.5 on 2 or more tests, or a z-score of less than or equal to -2.0 on a single test. RESULTS:: Approximately 46% of patients exhibited cognitive impairment at the time of assessment, which is significantly greater than would be expected considering healthy population norms (binomial test: P < .0001). Patients exhibited impairments in motor function, verbal learning, and executive function much more frequently relative to normative expectations (binomial test: P < .0001). CONCLUSIONS:: The prevalence of cognitive impairment in men with newly diagnosed NSGCT is unexpectedly high before the receipt of adjuvant chemotherapy. Efforts to track cognitive function over time and to develop effective interventions are warranted. Cancer 2010. (c) 2010 American Cancer Society