Measurements of critical heat flux (CHF) were performed for a horizontal annular channel (diameters 11.2 and 54 mm, approx. 1m heated length) in which the eccentricity in the vertical direction of the inner heater could be varied. Measurements for low mass fluxes (up to 1600 kg/m2/s) using freon-12 at a pressure of approx. 10.3 bar and saturation inlet conditions, show a strong influence of eccentricity on CHF; this influence is discussed on a basis of the flow pattern under which CHF occurs.