We have previously reported that treating triple-negative tumor bearing nude mice with intraperitoneal (ip) 10 mg/kg body weight of (S,E)-3-hydroxy-2-(2-hydroxybenzylidene)amino-N-tetradecylpropanamide, a ceramide analog, 5 days per week for 3 weeks, was shown not only to suppress tumor growth but also to reduce metastasis. Studies reported here focus on determining the toxicity of this drug in the nude mice. During the first study, treated animals (single intraperitoneal (ip) injection, 0, 40, 80 and 120 mg/kg body weight) were closely monitored for 14 days for any signs of illness or death. No mice were lost in any animal groups; however, hepatic serum enzymes were elevated, and hepatic and heart tissue damages were found in the highest dosage group. The subsequent study was performed using a lower dosage range (single ip injection, 0, 25, 50 and 75 mg/kg body weight), which resulted in no significant toxicity. All tested parameters were within normal ranges, with no observed irregularities. Our findings show that a single ip dose of this ceramide analog induced liver and heart toxicity at 120 mg/kg but not at doses of 80 mg/kg body weight or lower.