"Hello Mary Lou" is a song written by American singer Gene Pitney[3][4][5] first recorded by Johnny Duncan in 1960[6] and by Ricky Nelson at United Western Recorders Studios on March 22, 1961.

[10] The song features an influential guitar solo by James Burton, often cited by later guitarists such as Brian May.

Piano is by Ray Johnson, who had succeeded Gene Garf as Nelson's regular session pianist in November 1959.

[11] Other musicians on the record include Joe Osborn on bass and Ritchie Frost on drums.

"Hello Mary Lou" is similar to an earlier song, "Merry, Merry Lou", written by Cayet Mangiaracina and recorded by his band, the Sparks, in 1957 on a single released by Decca Records.