The music of Polish-Russian composer and pianist Mieczyslaw Weinberg has received international acclaim since his death in 1996, especially during recent years. Although many of his solo piano works were published, performed and recorded during his lifetime, including his 6 solo piano sonatas and 17 Easy Pieces, there were several solo piano compositions in his archives which have remained unpublished, unperformed and unrecorded for many years. Peermusic Classical in Hamburg, Germany obtained pdf copies of these compositions, which were subsequently included as part of the recordings of “Mieczyslaw Weinberg – Complete Piano Works Volumes I–IV” on Grand Piano/Naxos Records. Sonatina Op. 49 (1951) and its subsequent revised version as Sonata Op. 49b (1978) are two such works. There are interesting comparisons to be made between the compositional techniques Weinberg employedin each version, i. e. how he used the original material from the Sonatina in the Sonata revision, what changes he made and how he made them, including quotations from previous solo piano works inserted into the latter versions. It is also a notable fact that Weinberg, himself a virtuoso pianist, had ceased to compose for solo piano after 1960. The Sonata Op. 49b, “Can-Can” in Honor of Rastorguyev (1965), and Two Fugues (1983) present the sole exceptions, of these Sonata Op. 49b being the most compositionally substantial work. Keywords: Mieczyslaw Weinberg, Moisei Vaynberg, Dmitry Shostakovich, Jewish composers in the Soviet Union, Polish/Soviet composers in the 1950’s, Piano music in the Soviet Union during the 1950’s, folk music influences, Children’s Notebook.