In the period from the Fall of 1993 to the Winter of 1994, at the Cotaxtla Experimental Field, a research with the goal of determining the most efficient pre-emergent and post-emergent herbicides was performed, in order to control weeds in bean plantations in the optimal and most economic way. The dominant weeds at the experimental site were: Yellow Flower (Aldama dentata) and “pitillo” grass (Ixoporus unisetus). The pre-emergent herbicides: Metribuzina, 0.350 Kg i.a./Ha, Alaclor + Metribuzina 1.5 + 0.210 and 1.5 + 0.290 Kg i.a./Ha, were found to control grass and broad leaves in an acceptable way. The optimal treatment was that of Alaclor + Metribuzina 1.5 + 0.210 kg i.a./ha with a TMR of 1655% and an RBC of 10.6. The best post-emergent herbicide to control broad-leaf weeds and grass, was the mixture of Fluazifop Butil + Fomesafen 0.125 + 0.25 kg i.a./ha, as the most economic and optimal post-emergent with a TMR of 36% and an RBC of 6.3. We obtained the best yields with 1061 kg/ha. Imazethapyri Chlorimuron Ethyl were found to be highly toxic for the bean plant (100%).