The antimicrobial and cytotoxic activities of the leaf or flower ethanol extracts from Senna and Cassia species. Display omitted •Species belonging to the genera Senna or Cassia are widely used in Brazilian traditional medicine.•The antimicrobial and cytotoxic activities of the leaf or flower ethanol extracts from Senna and Cassia species were evaluated.•S. macranthera flower ethanol extract exerted significant antifungal activity that was correlated with a series of phenolic compounds. In Brazilian traditional medicine, botanical species belonging to the genera Senna and Cassia are widely used as laxative, analgesic, and antifungal agents to treat ringworm and other fungal skin infections. This has motivated us to select and to screen ten species of these genera for their antibacterial, antifungal, and cytotoxic activities. The leaf or flower ethanol extracts were investigated against aerobic and anaerobic oral bacteria and Candida spp.; the microdilution broth method was employed. Cytotoxicity was determined against Vero cells. Among the plant extracts evaluated herein, four extracts at 200.0–400.0 μg mL–1 presented moderate activities against at least two bacterial strains. Concerning the antifungal action, the S. macranthera flower ethanol extract exerted significant antifungal effect with MIC values ranging from 5.9 to 23.4 μg mL–1. This extract was submitted to liquid-liquid extraction, and the resulting fractions were tested. The ethyl acetate fraction showed better antifungal activity (MIC values of 5.9 μg mL–1 for C. glabrata and 23.4 μg mL–1 for C. albicans and C. tropicalis) as compared with amphotericin B (0.1–0.2 μg mL–1), used as positive control. The bioactive metabolites of this fraction were identified by UHPLC–ESI/HRMS/MSn, which revealed the presence of eighteen compounds, including one organic acid (1), two flavan-3-ol (2 and 3), one flavone (4), two glycosylated flavonols (5 and 6), five proanthocyanidin dimers (7–11b), and seven proanthocyanidin trimers (12–18). The antimicrobial activities of some Senna or Cassia species studied here have been reported for the first time. The present results show that S. macranthera flowers are an interesting source of new antifungal agents.