There have been many evaluations of the use of chlordiazepoxide in mental illnesses, most of these concerned with its use in the reduction of anxiety. The majority of the papers have emanated from North America and have reported in “open” investigations that the drug is of value in reducing anxiety. Other papers from Britain, Australia and the European Continent have also described the results of similar treatment. Of the British contributions, only two of eight (Jenner et al., 1961; Gore and McComisky, 1961) describe results of placebo-controlled trials. A recent annotation concerning chlordiazepoxide (1961) observed that most of the trials had not involved the use of placebo. Furthermore, as chlordiazepoxide is a drug very much more expensive than a barbiturate, it was considered that more placebo-controlled investigations were desirable.