Campylobacter spp. are one of the most frequent causes of bacterial diarrhea worldwide. Although severe diarrhea is not highly prevalent, the risk of a fatal outcome is increased when infection is caused by strains resistant to macrolides, fluoroquinolones, and/or tetracyclines. It is therefore necessary to test the susceptibility of these bacteria to other antibiotics such as colistin, which may serve as an alternative therapeutic option in these situations. The E-test was used to investigate the activity of erythromycin and colistin against 30 clinical isolates of Campylobacter spp. The MIC values obtained (range: 0.38-8 mg/liter) were sufficiently low, given the elevated concentrations that colistin sulfate can reach in the intestinal lumen, for this antibiotic to be considered useful to treat severe diarrhea caused by Campylobacter spp. resistant to first-line antibiotics.