A 57-year-old man requiring ventilation after gastric-tube reconstruction (due to oesophageal carcinoma) and a 16-year-old boy with thoracic trauma developed pneumonia caused by Pseudomonas aeruginosa and other pathogens. Their infections persisted during treatment with antibiotics. The antibiotic colistin was added and the clinical condition improved in both patients after 3-4 weeks. Eventually, they both were transferred to a rehabilitation clinic. The use of colistin was abandoned in the 1970s due to alleged nephro- and neurotoxicity. In recent observational studies, the drug appeared to cause fewer toxic side-effects than previously thought. Colistin is only registered for inhaled use for lung infections and for resistant pulmonary infections in patients with cystic fibrosis, but it may also be effective in the treatment of other patients with multidrug-resistant, Gram-negative bacteria.