On of the most interesting aspects of our medicinal plant investigation was the discovery of the pharmacological effects of the water codistillate for the processing of essencial oil (hydrolate). In the present investigation several hydrolates were tested on toad rectus abdominis, rabbit duodenum, rat uterus amphibia isolated heart. Among the hydrolates Endro (Foenculum vulgare), Alecrim de tabuleiro (Lippia gracilis), velame (Croton sp.), Marmeleiro branco (Croton nepetifolius) and Vandelia sp. were active. The following plants were devoided of effects: Laranja (Citrus araticum), Azeitona (Sizygium jambolana), Melosa (Hyptis crenata), Maracujá (Passiflora edulis), Pau d'óleo (Copaifera langsdorfii), limãozinho (Fagara sp.), Bananinha (Duguetia sp.) Hyptis sp., Samba coité (Hyptis sp.-10), Cravo de defunto, (Tagetes minuta), Camarazinho (Lippia sp.-15), Ata brava (Annona sp.-01), Araticum (Annona coreacea) and tipi (Petiveria alliacea).