Background: Rhabdomyolysis is a common and potentially life-threatening syndrome, with acute kidney injury (AKI) as a serious complication. There are only a few larger studies on the subject and there are no recent and relevant studies from Europe. Therefore, we did a ten-year retrospective study including all patients treated for rhabdomyolysis in a medical clinic, studying clinical characteristics, aetiologies, treatment, complications and mortality. Further, we studied correlations between CK, myoglobin and creatinine (as a marker of renal function and thereby AKI), and whether CK/myoglobin ratio could be a valuable tool in the diagnostics of this patient group. Methods: The study included all patients treated for rhabdomyolysis at the Department of Medicine, Oslo University Hospital, Ulleval, from 2003 and until the end of 2012. Rhabdomyolysis was defined as serum CK values greater than 5 times the upper limit of normal. Results: 341 patients met the inclusion criteria; 67% were males and median age was 54 years (range 17-99). AKI occurred among 51% and 10% were in need of dialysis. Mortality in the group as a whole was 4%. The most common aetiologies were immobilization (60%), prescription drugs (55%) and illicit drugs and/or alcohol (35%). Maximum serum CK and myoglobin correlated equally to creatinine values for the included patients. Logistic regression showed that myoglobin was better in predicting the development of AKI than CK. And CK/myoglobin ratio was a good predictor for AKI: lower values than 5.70 increased the likelihood of developing AKI, whereas higher values indicated that development of AKI was less likely. Conclusions: AKI was a common complication among patients treated for rhabdomyolysis in our medical department, and nearly one out of five of those needed dialysis. Serum myoglobin was a better predictor for AKI than CK, and CK/myoglobin ratio could be useful to assess the likelihood of developing AKI.