This study assessed the antiproliferative and genotoxic effects of Linum usitatissimum L. and Plantago ovata Forssk. plants used in Turkish traditional medicine for medicinal purposes. P. ovata and L. usitatissimum, which have a purgative effect, have been used extensively in recent years. The P. ovata plant has a large quantity of soluble fibre in the seed coat, while the seeds of the L. usitatissimum also have a large quantity of mucilage from the soluble fibres. In the present study, the genotoxic and antiproliferative effects of these species were examined using the Allium cepa L. test. As an experimental group, three different concentrations (for P. ovata-7.2 mg/mL, 14.4 mg/mL and 28.8 mg/mL; for L. usitatissimum- 20 mg/mL, 40 mg/mL and 80 mg/mL) were used (two different concentration series were used, taking into consideration the traditional usage quantities); purified water was used as a negative control, and methyl methane sulfonate (the DNA-alkylating agent MMS, 0.01 mg/mL) was used as a positive control. To evaluate the mitotic index (MI) and chromosome aberrations type (CA) of the A. cepa root-tip meristem cells, approximately 1000 cells per concentration group, including the controls, were numbered. For both extractions, it was observed that the root length decreased from the negative control to other concentrations, with the lowest length in the positive control. P. ovata and L. usitatissimum were found to cause alters in the rates of the MI relative to the negative control in A. cepa due to the increased concentration. The comet assay distinctly indicated that concentration-dependent DNA damage in the root-tip meristem cells of A. cepa were detected for the different concentrations of plant extracts. These results showed that P. ovata and L. usitatissimum aqueous extracts had increased concentrations that were above the recommended antiproliferative and genotoxic effects.