Oral rehydration therapy is a proven method for preventing mortality from dehydration due to diarrhoea. In rural Bangladesh a community based programme, called the Oral Therapy Extension Programme (OTEP), has been teaching mothers how to make and use an ORT solution using local household salt (lobon) and unrefined brown sugar (gur). The programme has been organised by a national non-governmental organization called the Bangladesh Rural Advancement Committee (BRAC). This programme plans to visit 16 million households throughout the country by 1990 and 5 million households had been visited by December 1985. The results from an earlier evaluation of the First Phase of the programme were encouraging. A further more detailed evaluation, which concentrated on determining the usage and safety of homemade lobon-gur solution, was undertaken in 1984 and this thesis presents the findings. The literature has been reviewed on the problem of diarrhoeal diseases and on the discovery of ORT and its applications. Methodological issues in undertaking the evaluation of such programmes are then considered. This evaluation focussed on usage and safety and was carried out using two main approaches, firstly through an indepth village case study and then by using a household sample survey. The cultural perceptions and practices regarding diarrhoea were studied in the village case study, which revealed that to the population there were four types of illnesses which all had the symptoms of diarrhoea. The sample survey found the usage of the ORT ranged from 2% to 55% of episodes, depending on how usage is defined. The ability of mothers to prepare the ORT solution was also studied and this showed that the ability, although originally good, has declined over time after teaching. The policy and programme implications of these results are discussed and recommendations are presented.