The value of serum C-reactive protein (CRP) levels as a predictor of complications in neutropenic patients needs to be further defined. We sought to identify an association between severe complications and daily CRP levels measured in 104 multiple myeloma patients during the 3 week period following high-dose melphalan and autologous transplant. Significantly higher mean CRP levels and CRP velocity of increase were observed among patients with severe complications. A cut-off point of 100 mg/l (CRP levels) and 15 mg/l/day (CRP velocity) identified patients likely to suffer severe complications with 86 and 75% sensitivity, respectively. Prospective validation of this model is currently underway.