Tomato investigations were carried out under greenhouse and field conditions. The aim was to determine the extent to which greenhouse conditions influence the chemical composition of tomato fruits. Plants grown under field conditions were used as the control. Tomato trials were performed during different periods. Greenhouse trials were carried out in the winter and the spring period (January-June), and field trials in the spring and the summer period (May-September). Zinc (Zn), iron (Fe) and copper (Cu) content was established in ripe tomato fruits. Greenhouse conditions were found to effect zinc and iron content in tomato, whereas copper content was unaltered.