Abstract: Pancreatic Lipase (PL) is the most important enzyme in digestion of triglycerides. One of the strategies in prevention or treatment of obesity is altering metabolism of lipids by inhibition of dietary fat absorption. One hundred plant extracts were prepared and botanically identified. The air dried plants were extracted with methanol. Anti lipase activity of each plant was determined by turbidimetric assay. Quercus infectoria, Eucalyptus galbie, Rosa damascena and Levisticum officinale showed more than 50% inhibition on the enzyme activity. Kinetic study of the enzyme was performed in the presence of effective extracts. Levisticum officinale showed mixed inhibition and Rosa damascena, Quercus infectoria and Eucalyptus galbie showed non-competitive inhibition by double-reciprocal Lineweaver-Burk plot analysis. Under the controlled condition, Km value for enzyme was 0.3 mM and Vmax was 0.078 mM min-1; Vmax in the presence of Quercus infectoria, Eucalyptus galbie, Rosa damascena and Levisticum officinale extracts were 0.051, 0.056, 0.049 and 0.068 mM min-1, respectively. Because of mixed inhibition, Levisticum officinale showed a different Km value of 0.617 mM. Further studies needed to elucidate the effectiveness of these active extracts in vivo and attempt should be made to purify their active components to be used as safer and cheaper therapeutic agents in future.