In this paper we report on the effect of different concentrations of lactose and galactose in the production of P-galactosidase by Kluyveromyces marxianus CBS6556. The results clearly demonstrate a decrease in enzyme specific activity during cultivation at high concentrations of L-lactose or D-galactose, despite the fact that these carbohydrates are normally used for induction of the beta-galactosidase activity. Therefore, maximum induction of beta-galactosidase in K. marxianus batch cultures was obtained at low concentrations of the inducer carbohydrates, in the range between 0.5 to 15 mM. Those informations can help to design low cost medium with higher beta-galactosidase productivity by K. marxianus cells.