Beef longissimus steaks from 40 bull carcasses were used to study the effects of electrical stimulation (ES) on meat color mechanisms and myoglobin properties. Total pigment concentration and ratios of myoglobin forms for ES and control (C) samples were not different. Color panel and several spectrophotometric measurements indicated ES produced a lighter, brighter-red color in displayed steaks. Disappearance of reduced myoglobin during blooming was similar in unaged C and ES steaks, but reduced myoglobin decreased faster during blooming of ES steaks aged 6 days. ES decreased anaerobic metmyoglobin reducing activity and induced more metmyoglobin formation when steaks were in a 1% oxygen atmosphere.