Oscar Castro-Neves, a Brazil-born guitarist who helped create the sensuous rhythms of bossa nova and orchestrated music for movies including “L.A. Story” and “Dirty Rotten Scoundrels,” died Sept. 27 in Los Angeles. He was 73.

The cause was cancer, his wife, Lorraine Castro-Neves, said.

Mr. Castro-Neves, who was noted for both his virtuosity and impish sense of humor, toured with jazz greats Dizzy Gillespie and Stan Getz. For 10 years, he was guitarist, musical director and vocal coach for Sergio Mendes’s Brasil ’66 and went on to produce albums by luminaries as varied as cellist Yo-Yo Ma and jazz harmonica player Toots Thielemans.

Oscar Castro-Neves was born May 15, 1940, in Rio de Janeiro, and was one of eight children in a musical family. With his mother playing guitar and an uncle playing cello, young Oscar took up the cavaquinho, a small, traditional Brazilian guitar, and piano.

“My uncle taught me the hip chords, and I was hooked,” he told jazz pianist Ramsey Lewis in a 2005 PBS interview.

At 16, he was a huge success. After a recording artist heard Mr. Castro-Neves play at a party, his composition “Chora Tua Tristeza” (Cry Your Sadness) rocketed to the top of the charts and was widely recorded by others.

One in a set of triplets, Mr. Castro-Neves and three of his brothers formed a quartet that would play in the neighborhood and practice in a garage. He asked musician Antonio Carlos Jobim over for a beer, and they soon were part of the emerging bossa nova, a sexy “new beat” that reflected the optimism, albeit passing, of a new Brazil.

“Bossa nova is naive, a little boat, the sun, the sea, the illusions,” he said in an interview years later. “ ‘I lost my girlfriend, but I will get her back tomorrow.’ ”

At 22, Mr. Castro-Neves performed in a landmark bossa nova concert at Carnegie Hall. In 1966, he moved permanently to the United States, where his quick, gentle guitar style and murmuring vocals received rave reviews as he toured with Getz, Frank Sinatra, Lalo Schifrin and others.

“Castro-Neves is incapable of creating a dull moment, but that is an understatement,” critic Leonard Feather wrote. “He is only capable of generating rhythmic, harmonic and melodic joy.”

With homes in San Diego and Los Angeles, Mr. Castro-Neves wrote the scores for a number of films, including “Blame It on Rio,” a 1984 romantic comedy; and his arranging and orchestrating credits include “Sister Act II” and “He Said, She Said.” He also wrote the music for Julia Louis-Dreyfus’s TV series “Watching Ellie.”

In addition to his wife, Castro-Neves is survived by two daughters and four grandchildren.

— Los Angeles Times