Little is known about adenovirus infections in adult organ transplant recipients. We prospectively assessed adenovirus infection in 263 transplant recipients using polymerase chain reaction (PCR) on plasma samples at regular intervals post-transplant. Adenovirus DNA was detected in 19 of 263 patients (7.2%). Viremia by transplant type was: liver (n = 10 of 121 [8.3%]), kidney (n = 6 of 92 [6.5%]) and heart (n = 3 of 45 [6.7%]). Time to viremia onset was within 10 days post-transplant (n = 4), on day 28 (n = 1), on day 100 (n = 7) and between months 6 and 12 (n = 7). At the time of viremia, 11 of 19 (58%) patients had no symptoms, 2 of 19 (10.5%) had gastrointestinal (GI) symptoms, 2 of 19 (10.5%) had respiratory symptoms and 4 patients (21%) had vague/non-specific symptoms. All patients recovered spontaneously. Only 1 of 19 (5%) patients had subsequent acute rejection. Adenovirus viremia is relatively common in adult liver, kidney and heart transplant recipients and most infections are asymptomatic, transient and self-limited. No serious clinical sequelae or effects on subsequent acute rejection were observed.