The study deals with the connection between metabolic syndrome (MS) and smoking habits of 1602 males and 828 females aged 18-97 years from the island of Hvar, Croatia. The age-adjusted prevalence of MS was higher in males (18.1-31.2%) than females (9.7-24.2%) by all five criteria that were defined, except the one by AHA/NHLBI. The overall prevalence of MS reached 12.9% by WHO using body mass index (BMI), 13.1% by EGIR, 14.5% by WHO using waist to hip ratio (WHR), 18.2% by NCEP/ATP III, 18.9% by AHA/NHLBI, and 26.7% by IDF criteria. The prevalence of smoking habits was similar in males (24.7%) and females (23.8%). The frequency of mild, moderate and heavy smoking was higher in males than females, 35.8:26.6%, 31.0:27.0%, and 35.9:7.7%, respectively. Age and sex had significant influence on BMI and WHR, both being highest in male former smokers (28.15 kg/m2 and 0.973, respectively) and in female non-smokers (27.18 kg/m2 and 0.869, respectively). The appearance of arterial hypertension (HTN) differed according to frequency of smoking; males had higher prevalence than females using WHO and EGIR criteria of blood pressure > or = 140/90 mmHg, even after age adjustment. In males and females respectively, systolic HTN in non-smokers was 20.7:15.1%, in former smokers 17.9:15.2% and in current smokers 16.9:13.0%; diastolic HTN in non-smokers was 19.8:12.7%, in former smokers 22.4:10.5%, and in current smokers 11.3:9.1%. By NCEP, AHA, IDF criteria of blood pressure > or = 130/85 mmHg, arterial HTN was also more prevalent in males than females; systolic HTN in non-smokers being 31.4:19.8%, in former smokers 29.9:12.7%, and in current smokers 25.4:11.1%; and diastolic HTN in non-smokers was 20.5:11.5%, in former smokers 24.8:11.3%, and in current smokers 14.7:9.4%. According to AHA/NHLBI and IDF criteria of high plasma glucose as > or = 5.6 mmoL/L, both males and females in all the three categories of smokers had glucose levels above the normal range (5.80-6.31 mmol/L in males and 5.80-5.91 mmol/L in females), except female current smokers (5.51 mmol/L). By WHO, EGIR and NCEP/ATP III criteria of high plasma glucose as > or = 6.1 mmol/L, only male non-smokers (6.31 mmol/L) and former smokers (6.24 mmol/L) had elevated levels. Considering normal HDL-cholesterol as > 1.0 mmol/L in males and > 1.2 mmol/L in females, both males and females in all the three smoker's categories had HDL within normal range; females having higher HDL levels (1.52 mmol/L) than males (1.30 mmol/L). Considering normal value for triglycerides as < 1.7 mmol/L, male former smokers (1.76 mmol/L) and current smokers (1.81 mmol/L) had higher levels; and as a whole group triglycerides were higher in males than females, 1.66:1.37 mmol/L respectively. The prevalence of MS differed between males and females using various MS criteria. Both males and females had the highest prevalence of MS by IDF criteria; male former smokers 60.5%, female non-smokers 51.4%, male non-smokers 53.8%, female former smokers 38.2%, and lowest in both male and female current smokers 39.8 and 33.0% respectively. In males, the lowest prevalence of MS was observed in non-smokers by AHA criteria (30.5%), in former smokers by WHO criteria (35.7%), and in current smokers using EGIR criteria (18.1%). Females in all the three smoker's categories had the lowest prevalence of MS using EGIR and WHO criteria. MS were less prevalent in current smokers than in non-smokers and former smokers.