The short-term effects of air pollution on morbidity in the Athens population were studied. Data were collected on the daily number of emergency outpatient visits and admissions for cardiac and respiratory causes (diagnoses at time of admission) to all major hospitals in the greater Athens area during 1988. Measurements of air pollution made by the Ministry of the Environment monitoring network included values for smoke, carbon monoxide, and nitrogen dioxide. Statistical analysis was done using multiple linear regression models controlling for potential confounding effects of meteorological and chronological variables, separately for winter (1/1-3/21 and 9/22-12/31) and summer (3/22-9/21). It was found that the daily number of emergency visits was related positively with the levels of air pollution, but this association did not reach the nominal level of statistical significance for most pollutants. The number of emergency admissions for cardiac and respiratory causes was related to a statistically significant degree with all indices of air pollution during the winter. Thus, the average adjusted increase in the daily number of cardiac admissions corresponding to an increase from the 5th to the 95th percentile of the season-specific distribution of each pollutant ranges from 15 to 17% or from 11 to 12.5 admissions per day, and for the daily number of respiratory admissions from 20 to 29% or from 8.3 to 12.1 admissions. The results of the present study indicate that air pollution in the Athens area has short-term effects on morbidity in the population.