Patient diaries have been used to ascertain patient’s views of the issues that trouble them during treatment. Both physical and psychosocial adverse effects are listed and can be further investigated. As an example, neuropsychological assessments of patients with cancer suggest that adjuvant chemotherapy may lead to cognitive impairment e.g. learning, memory, and attention deficits. However many of the early studies were cross sectional and lacked a control group. The pre-treatment function was unknown and so it was unclear what impact other treatments such as surgery with anaesthesia had. Many of the early studies were in breast cancer where hormonal changes and therapy could have been additional confounding factors. It is also important that appropriate measures of cognitive impairment that allows serial assessments were used. We performed a longitudinal study of men with either seminomas or non-seminomatous germ cell tumours where one group receiving chemotherapy because of their stage and histology can be compared to another group who had surgery only or surgery plus radiation therapy. Observations were made pre-surgery for those recruited early, and then 1 week, 1 month and 3, 6, 12 and 18 months post-surgery. For the cognitive testing we used a battery of computerized cognitive tests designed and validated for rapid and repeated use, having a game like quality by using playing cards, (CogHealth). Assessment of other factors thought to impact on cognitive function included self-perceived cognitive impairment, anxiety, depression, and fatigue. We recruited our final patient on 20th July 2012. Overall, 151 patients were recruited to the study. Of these, 51 are represented in the surgery-only cohort and 100 patients in the chemotherapy cohort. I will present the analysis of the post treatment changes in cognitive function within and between groups.