Gentamicin (GNT)-induced nephrotoxicity culminates into renal failure with a possible cardiovascular impact. Garlic extract (GE) is a cardiovascular protectant with limited mechanistic data. Therefore, we assessed the disturbance in specific cardiac parameters and the potential protective effect of GE supplementation against them in a rat model of GNT-induced chronic renal failure (CRF). Adult male rats (n = 24) were randomly assigned into four groups (n = 6 each): normal controls (CON), garlic extract controls (GE; 250 mg kg, orally), GNT-induced CRF (GNT; 100 mg kg, i.p.), and GNT + GE (GNT and GE in the same previous doses) groups. GNT and GE were given daily for 3 weeks. Animals co-treated with GNT and GE exhibited improved renal functions, body weight (BW), and heart weight (HW)/BW ratio; declined blood pressure; lowered plasma levels of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), and total peroxides (TP); and elevated total antioxidant capacity (TAC) levels. Moreover, the heart tissue contained raised levels of TAC and Na/K-ATPase activity and lowered levels of TP and Ca. Findings provide evidence that administration of GE in experimental CRF model helped protect the heart through reducing oxidative stress and controlling cardiac Na/K-ATPase activity and Ca levels.