D-004 is a lipid extract obtained from Cuban royal palm (Rosytonea regia) fruits, consisting of a mixture of fatty acids and esters. D-004 has shown protective effects on prostate hyperplasia induced by testosterone in rodents. We report the results of two studies investigating the acute and subchronic oral toxicity of D004 in rats. Oral acute toxicity of D-004 (2,000 mg/kg) was investigated in Sprague Dawley rats according to the acute toxic class method, and the results showed that D-004 oral acute toxicity was practically absent, being defined as unclassified. In the subchronic study, rats were orally treated with D-004 at 500, 1,000 and 2,000 mg/kg for 90 days. No evidence of treatment-related toxicity was detected. Thus, analysis of body weight gain, clinical observations, blood biochemistry, hematology, organ weight ratios and histopathological data did not show significant differences between control and treated groups. We conclude that D-004 orally administered to rats was safe and that no drug-related toxicity was detected even at the highest dose investigated in both acute and subchronic (2,000 mg/kg) studies. Thus, this dose can be considered as a nonobservable-effect dose in rats.