OBJECTIVE: THE OBJECTIVE OF THIS STUDY WAS TO COMPARE AND EVALUATE THE EFFICACY AND SATISFACTION OF ORLISTAT AND SIBUTRAMINE TREATMENT IN OBESE FEMALE PATIENTS AT ADISORN FORT HOSPITAL IN 2004. METHODS: A CROSS-SECTIONAL EXPERIMENTAL STUDY BY RANDOMIZED BLOCK DESIGN WAS PERFORMED. THE POPULATION WAS WOMEN AGE 18 TO 45 THOSE WHOM WANTED TO REDUCE THEIR WEIGHT (BMI>25) WITH ORLISTAT OR SIBUTRAMINE UNDER PHYSICIAN CONTROL AT ADISORN FORT HOSPITAL, THAILAND. SAMPLE WAS CALCULATED BY COHEN'S TABLE, SETTING ALPHA=0.05, BETA=0.2, POWER 0.80 EFFECT SIZE=2, SAMPLE SIZE (N)=40. WE ADMINISTERED ORLISTAT (360MG/D) OR SIBUTRAMINE (10MG/D) IN A RANDOMIZED, CONTROLLED, SINGLE-BLIND CLINICAL STUDY, AND EVALUATED WEIGHT AND SATISFACTION DURING SIX-WEEKS OF THIS TREATMENT. RESULTS: A TOTAL OF 40 FEMALES 36 +/- 4 YR WITH ORLISTAT; AND 40 FEMALES, AGED 37 +/- 6 YR WITH SIBUTRAMINE) COMPLETED SIX-WEEKS ON EXERCISE AND A CONTROLLED-ENERGY DIET. ORLISTAT WAS WELL TOLERATED, WITH GASTROINTESTINAL ADVERSE EFFECTS AS WELL AS INHIBITING THE ASSIMILATION OF FAT FROM THE BOWEL. IT WAS APPROVED FOR LONG-TERM TREATMENT OF OBESITY WHILE SIBUTRAMINE ACTED ON THE CNS TO CONTROL APPETITE OR ENHANCE THE FEELING OF SATURATION. SIGNIFICANT BODY MASS INDEX (BMI) IMPROVEMENT WAS DETECTED AFTER SIX-WEEKS (P<0.05) IN BOTH GROUPS (P=0.02, P=0.04 RESPECTIVELY). SIGNIFICANT WAIST CIRCUMFERENCE (WC), BUT NOT SIGNIFICANT HIP CIRCUMFERENCE (HC), IMPROVEMENT WERE OBSERVED IN BOTH GROUPS (P=0.03, P=0.14, P=0.04, P=0.21 RESPECTIVELY). ORLISTAT AND SIBUTRAMINE WERE NOT SIGNIFICANTLY DIFFERENT IN TERMS OF WEIGHT REDUCTION EFFECT (P=0.14). HOWEVER, PATIENTS WERE MORE SATISFIED WITH ORISTAT THAN SIBUTRAMINE (P=0.02). CONCLUSIONS: ORLISTAT AND SIBUTRAMINE COULD SIGNIFICANTLY REDUCE WEIGHT. HOWEVER, PATIENTS WERE MORE SATISFIED WITH ORLISTAT THAN SIBUTRAMINE.