A double-blind, placebo-controlled trial was performed to analyse the ability of Lactobacillus plantarum 299v to prevent further recurrent episodes of Clostridium difficile-associated diarrhoea (RCDAD). Recurrence of clinical symptoms (main outcome) was seen in 4 of 11 patients who received metronidazole in combination with L. plantarum 299v and in 6 of 9 treated with metronidazole in combination with placebo. The lactobacilli treatment had no side-effects. Although the small sample size does not allow any conclusion to be drawn concerning the efficacy of L. plantarum in patients with RCDAD, these results may contribute to the ongoing discussion about the benefits of probiotics in patients with RCDAD and encourage the performance of larger multicentre studies.