<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">The adsorption of the Alizarin Red S (ARS) and Patent Blue VF (PBVF) from aqueous solution onto agricultural waste mentha has been investigated. The effects of initial dye concentration, contact time, pH, temperature and ionic strength were studied in a batch system. ARS and PBVF adsorption onto mentha increased to minor extent with decreasing pH. Adsorption capacities of dyes increased with contact time, initial concentration, and temperature for both ARS and PBVF. Adsorption of ARS on mentha is more favorable than PBVF. The adsorption of ARS and PBVF was spontaneous and endothermic as concluded from thermodynamic assays.</span></span></p>