This study evaluated the chemical composition and anti-proliferative activity of essential oils (EOs) obtained by hydrodistillation from seven medicinal plants from Cachicadán, La Libertad Region, Peru. Limonene (0.64 to 44.43%) and linalool (0.36 to 2.12%) were identified in all EOs by gas chromatography coupled to mass spectrometry analysis. The major components (relative intensity ≥ 10%) were cisdihydro carvone, carvone, and cis-piperitone epoxide for Minthostachys mollis leaves; β-pinene, limonene, and ledol for Lepechinia heteromorpha leaves; limonene, neral, and geranial for Aloysia citriodora, both leaves and flowers; αpinene, and limonene for Myrcianthes myrsinoides leaves; and α-pinene, βmyrcene, and (E)-β-Ocimene for Dalea carthagenensis leaves. Constituted by (Z)β-ocimene, dihydrotagetone, (Z)-tagetone, and car-3-en-2-one, EO of Tagetes minuta leaves induced an irreversible cytostatic effect against MCF-7 human breast tumour cells. Further in vivo studies must be carried out to establish the safe and efficient dose of T. minuta EO as adjuvant treatment in oncological therapies.