In 1796, Beethoven wrote four pieces for piano and mandolin--this Sonatina, an Adagio in E flat, WoO. 43/2, and a Sonatina and Andante con Variazioni for piano & mandolin in D major, WoO. 44a and WoO. 44b, respectively. It appears that all four pieces were composed for the Countess Josephine de Clary, to whom Beethoven dedicated his aria for soprano and orchestra, Ah, perfido!, written around this same time. She would later become Countess von Clam-Gallas, and it would be in the library of her husband (and his brother) that the manuscripts of these four unusual works would be found.
This WoO. 43a Sonatina is a minor composition by the composer. It is delightful and colorful in its lightness, and, for its instrumentation, it is certainly a worthwhile effort. The mandolin happened to be a quite popular instrument near the end of the eighteenth century, drawing compositions from Mozart, Hummel and others. This Sonatina and the other three works Beethoven composed for piano and mandolin in 1796 are solidly-wrought, tuneful pieces that are rarely performed or recorded.
(Robert Cummings, Rovi, answers.com)