In 1987, situation of DHF in Thailand was the worst for the past 30 years. There were 152,840 cases and 785 deaths from the preliminary report. The incidence was highest ever reported. Outbreak begun early in January and reached its peak in July. All 73 provinces were affected except six provinces which had incidence of less than 60 per 100,000 population. The highest attack rates were in school children, especially 5-9 year olds. Virus isolation in a north-eastern province recovered Den-3 and Den-2 more common than other serotypes. Although a large outbreak in 1987 is unlikely to happen in 1988 but with the endemic areas all over the country there is a potential for small outbreaks to occur. The Ministry of Public Health needs new approaches and increased resources to control this disease.