In this research, the antibacterial activity of poly(acrylic acid-co-3-hydroxy-propionate) (PAcHP) was studied by disc diffusion, broth macrodilution minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods. For this purpose, three Gram-positive (B. subtilis NRRL B-209, M. luteus NRRL B-1018 and S. aureus ATCC 6538) and three Gram-negative (E. coli ATCC 25922, P. aeroginosa NRRL B-2679, P. vulgaris NRRL B-123) bacteria were selected. Firstly, antibacterial activity study was carried out by disc diffusion method using 100 microgram polymer. No bacterial growth was observed in B. subtilis plate, while the 29.63 mm inhibition zone diameter was obtained in the M. luteus plate. No inhibition zone diameters were observed in P. vulgaris, S. aureus, E. coli, and P. aeruginosa plates. The minimum inhibitory concentration (MIC) Broth Macrodilution and MBC method were then applied to four different polymer concentrations (25–50–75–100 mg/2 mL) in E. coli, S. aureus and M. luteus bacteria. There was no growth of S. aureus and M. luteus plaques in samples with 100 mg PAcHP /2 mL concentration. For this reason, it was concluded that the PAcHP polymer was bactericidal against three Grampositive bacteria in this study.