Latex samples from South American Moraceae have been examined for the presence of betaines. Tryptophan and tyrosine betaines were present in Maquira coriacea, Naucleopsis macrophylla, N. stipularis and N. ternstroemiiflora; this last species also had choline. Tryptophan betaine and choline were found in N. caloneura. Only trigonelline occurred in Pseudolmedia laevigata and P. laevis. On the other hand, no quaternary nitrogen compounds were detected in latex samples from M. guianensis, N. mello-barretoi, Castilla ulei, Helicostylis elegans and Perebea mollis subsp. mollis.