In recent reports polymyxins have been considered an effective and safe treatment option for the management of multidrug-resistant (MDR) Gram-negative bacterial infections. Here we report our clinical experience with the use of intravenous colistin sulfate in critically ill patients hospitalized from January 2006 to October 2008, as a last treatment resort in China, and assess its effectiveness and adverse effects. Fifteen patients who suffered from severe infections caused by MDR or pandrug-resistant (PDR) Gram-negative bacteria (13 isolates of Acinetobacter baumannii, 4 isolates of Pseudomonas aeruginosa and 2 isolates of Klebsiella pneumoniae), unresponsive to the initial empirical regimens, were treated with colistin sulfate (daily dose of 1.28 +/- 0.25 million IU and duration of 22.3 +/- 6.2 days), based on sensitivity results. The treatment resulted in a good clinical response in 73.3%, microbiological clearance in 60% and mortality in 20%. Possible nephrotoxicity occurred in 1 patient and no patients developed neurotoxicity. In conclusion, intravenous colistin sulfate is a safe and viable alternative for the treatment of severe infections due to sensitive MDR Gram-negative bacteria.