The results of the IMPACT trial showed a significant reduction in cytomegalovirus disease with 200-day valganciclovir prophylaxis compared to the standard 100-day regimen with the same drug. These results may have the potential to change the standard of care in most transplant centers. However, we have concerns with the design, execution and statistical analysis of this trial. Our study aimed to describe each of these issues and to provide possible solutions for the better understanding of the IMPACT trial. We conclude that the IMPACT trial does not have the strength of evidence to change current clinical practice of 100-day cytomegalovirus prophylaxis. Further, based on all available evidence, we consider that another clinical trial to test 200-day CMV prophylaxis is not necessary.