Intracerebroventricular infusion of 1-methyl-1,2,3,4-tetrahydro-beta-carboline (1-Me-THBC, tetrahydroharmane) in our earlier studies increased voluntary alcohol intake by rats when increasing ethanol concentrations were offered. We have now studied the possibility that, by using two fixed ethanol concentrations (11 and 20%, w/w), alcohol intake could also be increased. We find that 1-Me-THBC (1.13 mumol/day) does not increase alcohol intake. The animals appear unable to recognize the increase in ethanol concentration.