Herein, we describe our results on the determination of the chemical profile of the essential oil (EO) of flowers from Tagetes minuta L. grown in Southern Brazil. The major component of the EO is (Z)-tagetone 1 (70.64% w/w). Thiotagetone 6, a semi-synthetic derivative, was prepared from 1 in 82% yield. Compounds 1 and 6 and the EO were evaluated for their antioxidant and antifungal activities in vitro. All the tested samples presented antioxidant effect in scavenging radical and in the lipid peroxidation assays. A good antifungal activity against Candida lipolityca, Candida parapsilosis, Trichosporon asahii and Sphaceloma ampelinum was observed. (Z)-Tagetone 1 inhibited the mycelia growth of S. ampelinum around 80% at 6 days. No acute toxicity (200 mg/kg) was observed in mice for the EO or the compounds 1 and 6. The lack of toxicity is an indicative for additional studies aiming their potential therapeutic use.