The objective of this randomized, controlled study was to investigate the immunomodulating effects of a root preparation of Echinacea purpurea (EP) on canine parvovirus (CPV) and canine distemper virus (CDV) vaccination in dogs. Twenty-five healthy young poodles were randomly divided into 5 groups consisting of 5 dogs per group. All dogs were vaccinated with a modified live virus and observed for 3 days for adverse effects. Dogs in the experimental groups (groups 1-4) then received a daily oral preparation of EP dosed at 0.1g/kg, 0.2g/kg, 0.4g/kg, or 0.8g/kg with the fifth group of dogs remaining as untreated controls. After administering EP for 21 days, an additional 7-day observation period was conducted thus providing a total of 28 days on study. The serum antibody titers to CPV and CDV were determined by enzyme-linked immunosorbent assay (ELISA) on days 7, 14, 21 and 28 and results analyzed by one-way analysis of variance (ANOVA). Results showed that the antibody titers significantly increased after oral administration of EP in a dose dependent manner with dogs given 0.8g/kg (Group 4) demonstrating the greatest effect with statistically significant CPV and CDV antibody increases at all timepoints. The results of this experiment indicate that EP could be used as an immune enhancement agent for CPV and CDV vaccination in dogs.