OBJECTIVE Kanchnar guggulu is a compound Ayurvedic formulation used in clinical practice for the treatment of benign and malignant tumors. The present study investigates its cytotoxic and antiproliferative activities. METHODS The hydro-alcoholic (50%) extract of kanchnar guggulu was prepared. Its antimitotic activity was assessed in an Allium cepa assay, while its antiproliferative effects were studied in a yeast proliferation model. Methotrexate was used as a standard anticancer agent. RESULTS In the Allium assay, all concentrations of the extract (1, 2 and 3 mg/mL) and methotrexate (0.02 mg/mL) significantly inhibited the division of A. cepa root cells, decreasing root growth and mitotic index compared to control; this effect was concentration-dependent for kanchnar guggulu extract. In the antiproliferative studies, treatment with the hydro-alcoholic extract of kanchnar guggulu (1, 5 and 10 mg/mL) and methotrexate (0.025, 0.05 and 0.1 mg/mL) resulted in marked reduction of dividing Saccharomyces cerevisiae cells and inhibition of cell viability compared to control. The cytotoxicity of the hydro-alcoholic extract of kanchnar guggulu, shown by its antimitotic and antiproliferative effects, may be due to the presence of flavonoids and phenolics. CONCLUSIONS Kanchnar guggulu exhibited a cytotoxic effect by inhibiting cell division (antimitotic) and reducing cell proliferation. These results substantiate its potential for the treatment of cancer and support its traditional use in the treatment of cancer.