The present study was designed to examine the relationship between patients admitted to hospital for cardiovascular diseases (CVD) and meteorological and environmental factors. We tried a new approach by introducing the term “discomfort day”. An investigation into this relationship was made by classifying CVD into two different groups: a) acute myocardial infarction (AMI) with 2000 cases; b) angina pectoris (AP) with 3900 cases, on the basis of the code ICD-9-CM. The ratio of men to women was 2.1M / 1F for AP and 2.3M / 1F for AMI and the average age was 70 in both groups. Data for daily admissions for CVD was provided by the Administration of Careggi Hospital in Florence for the period 1998-2001. Hourly meteorological data was obtained from a station located in the city centre of Florence and the hourly chemical pollutants data obtained from the Regional Office for Environmental Protection in Tuscany. We characterized a “discomfort day” on the basis of threshold values of meteorological factors (temperature, relative humidity, wind speed, atmospheric pressure, global radiation and rainfall), three biometeorological indices (Heat Index, Wind Chill Index and Equivalent Temperature Index) and chemical pollutants (SO2, NO2, CO, O3 and PM10). We defined a “discomfort day” as a day which caused an impact on human health, in relation to specific diseases and linked to environmental and meteorological parameters. Two-by-two contingency tables on the relationship between frequencies of admissions, which occurred in so called “discomfort days” in comparison to those which were considered “comfort days”, were calculated to assess which meteorological and environmental factors have a statistically significant impact on hospital admissions. Both groups of CVD showed a different monthly distribution. Months with an average number of admissions significantly different in comparison with other months were July, August and October for AMI; August and November for AP. Threshold values of biometeorological indices describing discomfort days which are characterized by sultry conditions were associated with admissions for CVD in both men and women (P < 0.05). Discomfort days identified through low threshold values of Wind Chill Index (i.e. Wind Chill values lower than 10°C for at least 8 diurnal hours, P=0.0058) were significantly associated with admissions for AP in men. Discomfort days with a wide range of temperature (i.e. temperature range > 10°C, P=0.0040) showed an association with AMI in men. Discomfort days characterized by extended high values of air temperature (i.e. temperature higher than 30°C for at least 6 hours, P=0.00063 in women; P=0.0184 in men) were associated with admissions for AP. Discomfort days with a wide range of atmospheric pressure (i.e. atmospheric pressure range > 7mb, P=0.023) was also significant regarding AP in men.