Nocturne Op.55 No.1 in F Minor 夜曲 作品55之1 F小調

Composed in 1842–1844, the F minor nocturne has an average duration of about 5 minutes.

Structure
The piece is in ternary form (ABA). Its main theme has a slow 4
4 with a heavy, steady crotchet beat. It starts with the main theme which repeats once with only minor variations. The right hand plays a slow melody and the left hand accompanies with a bass note and then a chord, in crotchets. The second section is then played with, again, the right hand playing the melody and the left hand accompanying with bass notes and a chord. Although there are occasional changes to this pattern, for example the left hand plays a sustained minim with a crotchet chord above. The main theme then comes back in with some variations to the first two times it was played: a triplet phrase is added to the third bar of the section. The second section is again repeated with no variations, followed immediately by the first section again with the triplet sequence. A tempo change to più mosso speeds up the piece. It starts off with some fast, triplet quavers and then three loud (forte) chords. This then repeats three further times until a completely new section comes in with a melody in the right hand and triplet broken chords in the left (see score on left). A descending scale and some large chords completes this section and leads it onto the first theme again.

There is then a large variation on the first theme where the main tune is played with other notes in between. There is then a large section of arpeggios and finishing off on six final chords, then modulates to the parallel key of F major for an interrupted final cadence.

There are two short chorales. The first, at bars 71–72, marks the transition from B section back to A, while the second, at 98–101, concludes the piece, in F major.

The piece was described by Frederick Niecks (Chopin's biographer) as: "we will note only the flebile [feeble] dolcezza of the first and the last section, and the inferiority of the more impassioned middle section".

Op. 55, No. 1為F小調，長度約為5分鐘。右手部分以4/4拍的行板彈出緩慢的旋律，左手以一個低音接著一個和弦作伴奏。開首中第一主題出現兩次。然後是第二主題和加入三連音的變化的第一主題，並出現兩次。之後是標註Più Mosso（稍快）的和弦樂段，旋律共出現三次。然後是全新的旋律和左手部分的分解和弦。第一主題再度出現，但被大幅修改成連續的三連音，最後以6個闊和弦作結。樂曲的終結部分由F小調轉為F大調。

此曲曾於電視劇大西洋帝國中播出。電影末日戒備中一個恐怖份子頭目為音樂教師，他向一名小妹妹彈奏此曲以講述感受歌曲中細微差別的方法，後來電影更加入此曲的交響樂版本為背景音樂。