Since one of the main health problems of the indigenous population are infectious bowel diseases, we decided to test Mayan medicinal potions used to treat these conditions against some of the causal agents.Thirty-one herbal formulations used for the treatment of infectious bowel diseases were prepared according to the collected ethnobotanical data. Their activities were tested against some of the causal agents of diarrheic symptoms, such as Entamoeba histolytica, Giardia lamblia, Escherichia coli, Klebsiella pneumoniae, Salmonella typhi and Shigella flexneri.Nine formulations were active against bacteria (MIC=0.5 mg/ml), four on Entamoeba histolytica, and seven on Giardia lamblia (IC(50)≤20 μg/ml).This work supports the use of the traditional Mayan formulations against some infectious bowel diseases, and it is the first step towards their study.Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.