The objective of the present in vitro research was to determine cardiomyocyte function on poly lactic-co-glycolic acid (50:50 (PLA:PGA); PLGA) with greater amounts of carbon nanofibers (CNFs) and variations in CNF size, for myocardial tissue engineering applications. The addition of CNFs would increase conductivity and strength of pure PLGA. For this reason, different PLGA: CNF ratios (100:0, 75:25, 50:50, 25:75, 0:100 wt.%) were created and conductivity and cytocompatibility properties with human cardiomyocytes were determined. Results showed that PLGA:CNF materials were conductive and that conductivity increased with greater amounts of PLGA added, from 0 S.m-1 for 100:0 wt.% (pure PLGA) to 5.5x10-3 S.m-1 for 0:100 wt.% (pure CNFs) material. Furthermore, results indicated that cardiomyocyte density increased with greater amounts of CNFs of 200nm in diameter in PLGA (up to 25:75 wt.% , PLGA:CNFs). This study, thus, provided an alternative conductive scaffold using nanotechnology which should be further explored for cardiovascular applications.