AIMS: To identify the completeness of documentation of Complementary And Alternative Medicine (CAM) use in hospital medical records of patients before and after an education programme. METHODS: Documentation of CAM in all parts of the medical records was compared to patients' self-reported use. Data were collected for one month before and one month after an education programme for hospital staff. RESULTS: At baseline: 59 (58%) of 101 patients used 129 CAM in the month prior to admission; only 36 (28%) of the CAM were documented in the medical record. After education: 51 (54%) of 94 patients used 91 CAM in the month prior to admission; 40 (44%) of the CAM were documented in the medical record. After education, recording rates increased by 16% (95% CI: 3% to 29%) due to improvements by pharmacists (18%, 95% CI: 5% to 31%). 32 (54%) of CAM users at baseline and 29 (57%) of CAM users after education informed a health professional. The recording rates were only 23 (39%) and 28 (55%) respectively for patients in these two sub-groups, being an improvement of 16% (95% CI: -2% to 34%). CONCLUSIONS: Prevalence of CAM use among patients admitted to hospital is high, but documentation of usage is low. Strategies need to be designed to improve health professionals' knowledge about the need to record history of CAM use.