The structure and configuration of a new homoproaporphine, robustamine cis-N-oxide, isolated from Merendera robusta (tam. Liliaceae) have been established by spectral characteristics and chemical transformations. It was found that the fraction of alkali-soluble bases from this plant consists mainly of the homoaporphine compound merenderine, the amount of which increases considerably towards the end of the vegetation period. We have previously [1] given some results of an investigation of the total alkaloids of Merendera robusta Bge. growing in Kyzyl-Kum (Bukharskaya oblast). We detected the presence in the plant of, together with known tropolone alkaloids and their photochemical isomers, a series of compounds not containing the tropolone ring, two of which were isolated in the crystalline form. The structure of one of them - robustamine - was established.