Background: Infection with cytomegalovirus (CMV) remains a potentially serious complication in transplant patients. In this study we explored the risk factors for CMV infection in the 12 months following a solid organ transplantation (n = 242) in patients monitored for CMV infection from 2004 to 2007. Methods: CMV infection was defined as 2 consecutive quantifiable CMV-polymerase chain reaction (PCR) values or 1 measurement of >3000 copies/ml. Data describing pre- and post-transplantation variables were extracted from electronic health records. Time to CMV infection was investigated using Cox proportional hazards analysis. Results: Overall, 31% (75/242) of solid organ transplant patients developed CMV infection: 4/8 (50.0%) heart, 15/43 (34.9%) liver, 30/89 (33.7%) lung and 26/102 (25.5%) kidney transplant patients. The risk of CMV infection according to donor (D)/recipient (R) CMV serostatus (positive + or negative-) was highest for D+/R-(adjusted hazard ratio 2.6, 95% confidence interval 1.6-4.2) vs D+/R+, and was reduced for D-/R+(adjusted hazard ratio 0.2, 95% confidence interval 0.2-0.8) vs D+/R+. Conclusion: Positive donor CMV-serostatus is a major risk factor for CMV-infection in CMV-na ve recipients, but also in recipients with positive CMV-serostatus. Conversely, if donor is CMV serostatus is negative, the risk of CMV infection is low, irrespective of recipients CMV-serostatus. These findings suggest poorer immune function towards donor-induced strains of CMV versus recipient own latent strains.