We investigated the cricoid pressure technique of 135 anaesthetic assistants attending the annual conference of the British Association of Operating Department Assistants in May 1997. Their knowledge and training were assessed using a structured interview. Technique was assessed using a simulator measuring applied force during sham cricoid pressure. Our additional aims were to see whether a knowledge of the required force and practical training in the application of a target force would affect performance. Our results highlight a lack of knowledge relating to the manoeuvre. Only about one-third of subjects could quote an appropriate force and fewer than half could give a single contraindication to its use. Very few subjects had been trained on a model before practising the technique on a patient. Technique was poor and we observed a large variation in the force actually applied. Performance, as assessed by the variability of forces applied and proportion of subjects applying force within our target range (30-44 N), was improved markedly by providing simple instruction about the required force in an understandable form. Performance was further improved by practical training in the application of target force on a simulator.