Mammography was done with a conventional molybdenum anode/filter combination and either a molybdenum/rhodium (Mo/Rh) or rhodium/rhodium (Rh/Rh) combination to compare the contrast characteristics and penetrating ability of the different techniques. Each pair was rated as being equal, one slightly better than the other, or one much better than the other. The "preferred" image was also selected. The entrance surface exposure and the mean glandular dose were determined for each exposure. Mo/Mo was compared with Mo/Rh in 26 patients and to Rh/Rh in 23. Mo/Mo was judged to produce better or equal contrast and penetration in all cases except one using the Mo/Rh combination. Mo/Rh was the preferred image only once and Rh/Rh not at all. In comparison to the conventional Mo/Mo technique, the average dose was reduced by approximately 25% with Mo/Rh and by 50% with Rh/Rh.