The quantification of exogenous lactobacilli in faecal samples is frequently required for the evaluation of the intestinal colonization by probiotic bacteria. In this study, a selective and differential medium, designated LPSM, was developed for the culture of exogenous Lactobacillus plantarum. In quantitative assays, LPSM showed a sensitivity similar to those of enriched and Lactobacillus-adapted media. The presence of ciprofloxacin made LPSM inhibitory to most intestinal bacteria, including endogenous acid lactic bacteria, whereas exogenous L. plantarum strains grew producing a yellow color caused by acid production from sorbitol in the presence of bromocresol purple. The results showed that LPSM is suitable for detection and enumeration of L. plantarum in faecal samples.