The Adagio in E major for Violin and Orchestra, K. 261, was composed by Wolfgang Amadeus Mozart in 1776. It was probably a replacement movement for the original slow movement of his Violin Concerto No. 5 in A. It is believed that Mozart wrote it specifically for the violinist Antonio Brunetti, who complained that the original slow movement was "too artificial."[1] The work is scored for solo violin, two flutes, two horns and strings.

\relative c'' {
\override Score.NonMusicalPaperColumn #'line-break-permission = ##f
  \key e \major
  \tempo "Adagio"
  b4\f a16(gis) a(b) b8..( bis32 cis8) r | a4\p gis16(fis) gis(a) a8..( ais32 b!8) r | gis4\f fis16(e) dis(e) a4 gis16(fis) e(dis) | b'8\p( bis) cis (fis) e16(dis) cis(b) ais(b) a(fis) |

It is one of the few compositions Mozart wrote in the key of E major: Piano Trio No. 4, K. 542; the incomplete Horn Concerto, K. 494a; the incomplete fugue, Anh. C27.10.