Carthamus tinctorius L., or safflower, is an annual herbaceous crop belonging to the family Asteraceae, which is cultivated throughout China and used as a traditional Chinese medicine. Our previous study revealed anti-Parkinson's disease effects of an isolated standardized safflower flavonoid extract (SAFE). The purpose of this study is to evaluate the potential sub-chronic toxicity of SAFE. Male and female Sprague Dawley rats received three doses of SAFE (100, 300, and 500 mg/kg) q.d. by gavage for four weeks. Body weights were measured during the experiment, and blood samples were collected once per week for hematological and serum biochemical parameters. Major organs were examined after execution and histopathological analyses were performed. Body weight gain in the administration groups showed no decline compared to the control group. However, there were changes in values of aspartate transaminase (p < 0.05), alanine transaminase (p < 0.05), and blood glucose (p < 0.05) between treatments. SAFE influenced parameters related to platelets in rats receiving SAFE for both sexes under different dosages (p < 0.05). No histopathological changes were observed. SAFE might have influence on conglomeration of platelets, transaminases, and blood glucose. SAFE caused no significant toxicity and further studies may be needed to ensure safety of SAFE.