Objectives: Clostridium difficile diarrhoea (CDD) cases treated with intravenous immunoglobulin during a 2 year period were reviewed to determine disease severity and response to treatment. Patients and methods: Of 580 CD cytotoxin-positive patients, five received intravenous immunoglobulin because of protracted and/or recurrent CDD (median duration 50 days, range 45–64); two had biopsy‐ proven pseudomembranous colitis. The five patients received a median three non-CDD antibiotic courses (range 2–8). Indices of CDD severity included hypoalbuminaemia (n = 5, median 27 g/L, range 11–29), marked hypokalaemia (n = 3, range 1.9–2.7 mM), markedly raised peripheral white cell count (n = 3, 18–34 × 109 cells/L), abdominal signs (n = 3) and pyrexia (n = 1). The five cases received metronidazole for median 17 days (range 0–63) plus vancomycin for median 14 days (range 10–42) before intravenous immunoglobulin. One also received rifampicin plus vancomycin and one was given Saccharomyces boulardii. Results: Intravenous immunoglobulin was given at a dosage of 300–500 mg/kg (most commonly 400 mg/kg) for one dose (two patients), two doses (two patients) and in one case for six doses. The latter patient died of intractable CDD, three had a good therapeutic response to intravenous immunoglobulin and CDD recurred within 6 weeks in one case. In the three successfully treated cases, CDD resolved within 11 days. Conclusions: Intravenous immunoglobulin is useful for the treatment of intractable and severe CDD. Controlled studies are needed to assess the true value of this and other forms of passive immunotherapy.