Mineral salts, natural oils and some natural extracts were evaluated for its efficiency as potential fungicides against Alternaria alternata, the causal of tomato fruit rot. Obtained results showed that potassium sulphate (K2SO4) at 3% inhibited A. alternata growth to 66.6%, followed by magnesium sulphate (MgSO4) which reached 52.2%. In vitro studies indicated that ethanol extract of clove at concentration of 100 μl/100ml caused fungal growth inhibition reached 92.4%, while jojoba oil caused 44.8% growth inhibition. Moreover, when chitosan applied at 6mg/ml, it caused reduction in A. alternata growth reached 66.12%. Moreover, results of the in vivo studies indicated that applying of K2SO4, clove extract, chitosan solution and thyme oil reduced the diameter of lesions caused by A. alternata on infected tomato fruits. On the other hand, storage of tomato fruits at 13°C increased the efficacy of tested treatments. Obtained results showed the possibility of using K2SO4, clove extract, thyme and chitosan to control tomato postharvest fruit rot caused by A. alternata.