This prospective, longitudinal cohort study investigated the effect of donating or receiving a kidney on quality of life and relationship dynamics. Forty donors and 35 recipients from two UK transplantation centres completed the World Health Organisation quality of life questionnaire (WHOQOL) with additional questionnaires before, 6 weeks and one year after operation. Before donation the donor mean quality of life score in the physical domain was 18.8. This was significantly higher than the UK value for a healthy person of 16.4 (P < 0.001). Six weeks after operation, donor score reduced to UK normative levels however improved again at one year (17.7). Recipient mean physical domain score before was 11.4, significantly lower than the UK norm (P < 0.01), increasing to 16.0 one year after. Both donor (P < 0.009) and recipient (P < 0.05) experienced a significant improvement in their mutual relationship. Recipients expressed anxiety about the donor before operation. Donors were not concerned about living with one kidney. We concluded that living kidney donation has no detrimental effect on the physical or psychological well being of donors one year after donation. Transplantation results in a major improvement in quality of life for the recipient. Most donors would donate again, if this were possible.