A "cholera diagnostic kit" was developed for sensitive, specific, rapid, and inexpensive detection of Vibrio cholerae 01. The monoclonal antibody specific to antigen A of Vibrio cholerae 01 was used as an antigen detection reagent and the principle of dot-blot ELISA was adopted. The kits were used in seven Regional Medical Sciences Centres, Ministry of Public Health, located at various regions of Thailand where diarrhea occurs frequently. Diagnostic efficiency of the kits in the detection of Vibrio cholerae 01 from rectal swabs of the diarrheic patients and their household contacts was evaluated in comparison with the conventional culture method. The two methods were found to have excellent degree of agreement (kappa values > 95%). The dot-blot ELISA has several advantages over the culture methods, ie rapid (dot-blot ELISA takes 1-2 hours while the culture method takes at least two days) and inexpensive. It requires no sophisticated equipment. The procedure is not complicated thus it is easy to train personnel. The diagnostic kits are recommended for use in the detection of severe diarrhea caused by V. cholerae 01 not only in hospitals and health centres where adequate treatment of the patients is required as a life-saving measure but also for early recognition of cholera cases and their contacts so that other action, ie prevention and control of outbreaks and surveillance can be promptly implemented.