This study sought to determine the prevalence of metabolic syndrome, using data collected from 4,541 adults aged 20 years and over covered in the Fifth National Nutrition Survey conducted in 1998. The metabolic variables analyzed were: total cholesterol, LDL-c, HDL-c, triglycerides and fasting blood glucose. In addition, measurements of obesity such as body mass index (BMI), waist-to-hip ratio (WHR) and waist circumference (WC) as well as blood pressure were taken. Comparing the mean metabolic characteristics of the non-obese, total obese and the android obese, results showed significant differences in almost all the variables except for the HDL-c. By gender, non-significant differences were observed between males and females in the non-obese group in terms of the BMI and glucose levels and in the android group, in terms of total cholesterol. In all three groups, the biggest difference was observed in the mean triglycerides, where males had significantly higher mean than the females. Comparing adults with >125 mg/dl fasting blood sugar (FBS) there were higher rates of hypertension, high waist-to-hip ratio (WHR), high cholesterol, high triglycerides, high LDL-c, low HDL-c, among the overweight and obese than among those with normal BMI. In general, the proportion of subjects with co-morbid factors increased with higher levels of FBS, except for high cholesterol wherein no pattern was established. The highest prevalence of high FBS was found in both males (35.8%) and females (14.5%) with the following combined characteristics: high BMI, high WHR and high WC. Males with co-existing high BMI, high WHR, and high WC were observed to have the highest prevalence rate of hypertension (66.5%). Among females, the highest prevalence rate of hypertension (37.9%) was seen among those with high fasting blood sugar. The proportion of subjects with hypertension generally increased with age irrespective of the BMI status. One of the significant correlates of high FBS is waist-hip ratio. Males with WHR of equal or greater than 1 have almost six times the risk of having high FBS, while females with WHR of equal or greater than 0.85 have five times the risk of having high FBS compared to those with normal WHR. Among females with triglyceride levels of equal or greater than 200 mg/dL, the risk of having high FBS is five times compared to those with triglyceride levels below 200 mg/dL. Univariate analysis to see the effect of the type of obesity to dyslipidaemia and hypertension revealed that females with high waist circumference generally provided greater risk compared to those who were overweight and obese as well as those with android obesity. For males, high waist circumference had greater risk of developing high triglyceride and high LDL-c. Android obese males had greater risk to high FBS. The results showed that the prevalence rate of metabolic syndrome is 0.28%, based on the number of individuals with the following characteristics: high FBS, hypertensive, android obese, with body mass index (BMI) of > or =25.0 and high WC. Females had a higher rate than males - almost twice. Considering that metabolic syndrome, with its co-morbidity factors is prevalent among some Filipino adults aged 20 years and over, it is recommended that health programs geared towards minimizing the morbid risk factors be properly developed, promoted and fully implemented.