Abstract: The aim of this study was to evaluate the effect of Curcuma zedoaria, Curcuma mangga and Cuminum cyminum on rumen ecology and Pb profile in the rumen of mastitis dairy cows (in vitro). The research design was complete randomized design with 4 treatments (A Control (without herbs), B Curcuma zedoaria 0.02% of b.wt., C Curcuma mangga 0.06% b.wt. And D Cuminum cyminum 0.03% b.wt.) and 8 replication. This study was carried out in vitro in the laboratory by a pressure transducer technique (using rumen fluid of FH dairy cows. Sample was conditioned by adding 3 ppm Pb sulfate in rumen fluid. The variables measured were rumen pH, rumen bacteria counts (CFU mL–1), Volatile Fatty Acids (VFA) partial concentration (mg/100 mL) by using Gas Liquid Chromatograph (Chrompack® CP90022) and heavy metal Pb profile in rumen fluid by using Absorption Atomic Spectrophotometer (AAS) 6300 A with minimum reading limit 0.01 ppm. The result of study group of Curcuma zedoaria and Cuminum cyminum showed the highest number of rumen bacterial acetic acid, propionic acid and butyric acid and a lower profile of heavy metals in rumen fluid. Lead (Pb) was found only in the control without herb use.