Normal values for the various serum protein fractions of Merino sheep in South Africa have been established. Use was made of cellulose acetate membrane electrophoresis by the microzone technique and after processing the data these were plotted on cumulative relative frequency curves. Some sex differences in the values for albumin and globulins are apparent. The albumin fraction was found to be higher in rams and wethers than in ewes. Age differences are also apparent particularly with respect to the values for total serum protein and albumin which are lower in lambs and young animals than in adult sheep. The precision of the microzone technique has permitted a re-appraisal of the albumin: globulin ratio in ovine blood.