Mareya micrantha (Euphorbiaceae) is an Ivorian medicinal plant widely used in gastrointestinal disorders. So as to understand and identify metabolites possibly implicated in the activity of the plant on intestinal muscles, this study has been undertaken. From the crude ethanolic extract EE of the leaves, hexanic (EH), chloromethylene (EC), ethyl acetatic (EA) and butanolic (EB) sub-extracts were prepared as well as the hydroethanolic residual phase dried (Ar) and their effects on the isolated duodenum of rabbits were determined. If the sub-extracts EH, EA and EB, but also Ar, confirmed the myostimulant activity of the crude extract EE, this was not the case of EC which showed myorelaxant activity. This sub-extract, subjected to purification, led to the isolation of three major triterpenoids type 29norcucurbitacin (1-3) whose structures were confirmed using the combined analyses of their spectroscopic data (UV, MS, 1D NMR and 2D). All these molecules have shown myorelaxant activity, the most significant one being 2 with an IC50 value of 36.9 µM. These molecules would act by blocking both intracellular and extracellular calcium.