Tomato plants cv Naomi were grown in posidonia (Posidonia oceanica (L) Delile) with two NaCl salinity levels in nutrient solution (EC: 3 and 6 dS m−1) or with the NaCl level 3 dS m−1, in the most frequently used substrate in soilless systems, eg rockwool, to determine the effect of substrate or EC on yield, contents of minerals, antioxidants with nutritional and health values (vitamin C, lycopene, α-tocopherol and glutathione) as well as parameters affecting the organoleptic quality in cherry tomato fruits. Total yield was not influenced by substrate, but it was higher with 3 dS m−1 than 6 dS m−1 salinity. The yield reduction was compensated by the improvement of dry matter, total soluble solids, vitamin C and α-tocopherol, while lycopene and glutathione contents were not affected by NaCl. On average, when tomato plants were grown in the presence of the higher NaCl level, the fruit diameter was between 25 and 35 mm (considered optimal for cherry tomato) while, with 3 dS m−1, it was greater than 35 mm. Copyright © 2004 Society of Chemical Industry