Aim. We evaluated the effect of Spirulina maxima and Ascophyllum nodosum on the growth of one lactobacillus strain (Lactobacillus Paracasei subsp. Paracasei F19) and two enterococci (Enterococcus casseliflavus IM416K1, Enterococcus faecalis IM388C). Methods. Bacterial growths were evaluated by plating all strains into a 96-well microplate in triplicate and then reading the O.D. values at a wavelength of 595 nm at 0, 2, 4, 6, 8, 20, 26 and 28 hours by means of a microplate reader. Results. A growth inhibition occurred both for Enterococcus casseliflavus IM416K1 and Enterococcus faecalis IM388C (P<0.01) in presence of any Ascophyllum nodosum concentration, whereas a growth enhancement was observable at lower concentrations of Spirulina maxima and Ascophyllum nodosum (0.2, 0.4 and 0.6 mg mL-1) for Lactobacillus Paracasei subsp. Paracasei F19 (P<0.0001) and at lower concentrations of Spirulina maxima for Enterococcus casseliflavus IM416K1 and Enterococcus faecalis IM388C (P<0.0001). Conclusion. In conclusion, these preliminary experiments demonstrated that bacterial growth enhancement or inhibition may be influenced by Spirulina maxima and Ascophyllum nodosum concentration.