The economic crisis in Thailand in July 1997 had major social implications for unemployment, under employment, household income contraction, changing expenditure patterns, and child abandonment. The crisis increased poverty incidence by 1 million, of whom 54% were the ultra-poor. This paper explores and explains the short-term health impact of the crisis, using existing data and some special surveys and interviews for 2 years during 1998-99. The health impacts of the crisis are mixed, some being negative and some being positive. Household health expenditure reduced by 24% in real terms; among the poorer households, institutional care was replaced by self-medication. The pre-crisis rising trend in expenditure on alcohol and tobacco consumption was reversed. Immunization spending and coverage were sustained at a very high level after the crisis, but reports of increases in diphtheria and pertussis indicate declining programme quality. An increase in malaria, despite budget increases, had many causes but was mainly due to reduced programme effectiveness. STD incidence continued the pre-crisis downward trend. Rates of HIV risky sexual behaviour were higher among conscripts than other male workers, but in both groups there was lower condom use with casual partners. HIV serosurveillance showed a continuation of the pre-crisis downward trend among commercial sex workers (CSW, both brothel and non-brothel based), pregnant women and donated blood; this trend was slightly reversed among male STD patients and more among intravenous drug users. Condom coverage among brothel based CSW continued to increase to 97.5%, despite a 72% budget cut in free condom distribution. Poverty and lack of insurance coverage are two major determinants of absence of or inadequate antenatal care, and low birthweight. The Low Income Scheme could not adequately cover the poor but the voluntary Health Card Scheme played a health safety net role for maternal and child health. Low birthweight and underweight among school children were observed during the crisis. The impact of the crisis on health was minimal in some sectors but not in the others if the pre-crisis condition is efficient and healthy and vice versa. We demonstrated some key health status parameters during the 2-year period after the 1997 crisis but do not have firm conclusions on the impact of the economic crisis on health status, as our observation is too short and there is uncertainty on how long the crisis will last.