Mandarin is a plant species which belongs to the group of winter seasonal fruit. It is highly valued for its vitamin C, potassium and magnesium content. When buying mandarins, consumers do not have the information on the exact mineral composition of mandarins so a study was conducted to determine the content of macroelements potassium and magnesium in mandarins as well as to compare the results with regards to the place of purchase of individual samples. Mandarin sampling was carried out in the city of Zagreb at 3 markets, 3 retail chains and 3 organic product stores. After digestion with concentrated HNO3 and HClO4 in microwave oven, potassium was determined by flame photometry and magnesium by atomic absorption spectrometry. Dry matter was determined gravimetrically by drying until constant mass. The content of dry weight in the mandarin samples ranged from 7,86 % to 8,70 %. The content of potassium in dry weight of mandarin ranged from 2,04 % to 2,33 %, and the content of magnesium from 0,101 % to 0,110 %. The content of potassium in the fresh weight of mandarin ranged from 235 to 297 mg K/100 g fresh weight, and the content of magnesium ranged from 11,6 to 14,0 mg Mg/100 g fresh weight.