His death was announced on his official Web site, hubertsumlinblues.com. No cause was specified.
Mr. Sumlin began appearing on Howlin' Wolf's recordings in 1953, first as a rhythm guitarist and then, beginning in 1955, on lead guitar. Mr. Sumlin's eerie guitar counterpart to Howlin' Wolf's unearthly moaning on the 1956 hit Smokestack Lightnin' has lately been featured in a television commercial for Viagra. He also played lead on Back Door Man," Spoonful" and The Red Rooster," all written and arranged by the Chicago blues trailblazer Willie Dixon.
Dixon's often astute novelty lyrics and shrewd arrangements were topped off by Sumlin's imaginative, angular, taut attack, frequent glisses, maniacally wide vibrato and percussive chords, all drawn with an exaggerated brush," the producer Dick Shurman observed of Mr. Sumlin's relentlessly inventive playing in his liner notes to a 1991 boxed set of Howlin' Wolf's work for Chess Records.
Back Door Man," Spoonful" and The Red Rooster" were later made even more famous in versions released, respectively, by the Doors, Cream and the Rolling Stones. All three originally appeared on Howlin' Wolf's 1962 LP Howlin' Wolf," which the critic Greil Marcus called the finest of all Chicago blues albums," largely because of Mr. Sumlin's contribution.
Though at times tempestuous, Mr. Sumlin's partnership with Howlin' Wolf lasted until the singer's death in 1976. Mr. Sumlin's intuitive, empathetic accompaniment typically spurred his mentor to unpredictable and frenzied heights.
Speaking of their collaborations in a 1989 interview with Living Blues magazine, Mr. Sumlin said: Hubert was Wolf, Wolf was Hubert. I got to where I knew what he wanted before he asked for it, because I could feel the man."