Abstract: Cucurbitine is a novel amino acid with schistosomicidal activity. In an attempt to enhance its activity by modification of its chemical structure, some related compounds were synthesized. 1,2-Dicarbethoxy-pyrrolidin-4-one was converted into the corresponding ketoxime. Catalytic hydrogenation of the latter compound under atmospheric pressure and subsequent hydrolysis gave racemic 4-allo-hydroxyproline. However, reduction under high pressure, 4-aminopyrrolidine-2-carboxylic acid (Ⅲ_a) was obtained. A number of derivatives of cucurbitine, including some esters and acylamino compounds (Table 1) were also prepared. Pharmacological examinations revealed that none of the compounds prepared was more active than cucurbitine.