OBJECTIVE: The study was aimed to investigate expenditure and categories of herbal product consumption. METHOD: The scope of herbal products covered traditional drugs and health food. The consumption was estimated at retail prices based on expenditure at wholesale prices. The expenditure at wholesale prices was collected from drug stores in the whole country. Sampling technique was started at dividing the country into 13 regions. One province was selected from each region by convenience sampling method. Drug stores in each province selected were categorized into 3 types based on registration i.e. type 1 (eligible to sell all drugs), type 2 (eligible to sell ready-packed modern and traditional drugs) and type 3 (eligible to sell traditional drugs). Then, the drugstores were included at a proportion of 1% of the population in each type by convenience sampling method. Purchasing documents of herbal products of the drugstores were collected for two consecutive months. Data collecting period was during September and December 2001. RESULTS: The findings resulted from 129 drugstores. Total consumption of herbal products at wholesale prices was Baht 1530 million in the year 2001. Average mark-up calculated from a certain number of herbal drugs was 50.42% (95%CI=45.73, 55.11). Based on the mark-up, the consumption amount at retail prices was estimated at Baht 2,301 million. The top five rank of highest amount of products used were haematonics, anti-constipation, flatulence, anti-cough and antipyretics. Their values were Baht 313 million, Baht 303 million, Baht 255 million, Baht 252 million, and Baht 180 million, respectively. CONCLUSION: In terms of research methodology, the results from this study were relatively most reliable ever since. Therefore, they should be used in health and business planning.