Mushrooms represent a remarkable and yet largely unexplored source of new, biologically active natural products. In this work, we report on the xanthine oxidase (XO) inhibitory activity of 47 wild-growing mushrooms native to Hungary. Aqueous and organic (n-hexane, chloroform, and 50% methanol) extracts of selected mushrooms from different families were screened for their XO inhibitory activities. Among the 188 extracts investigated, the chloroform and 50% methanol fractions proved to be the most effective. Some species exhibited high inhibitory activity, e.g., Hypholoma fasciculare (IC50 =67.76 ± 11.05 µg/mL), Suillus grevillei (IC50 =13.28 ± 1.58 µg/mL), and Tricholoma populinum (IC50 =85.08 ± 15.02 µg/mL); others demonstrated moderate or weak activity. Additional studies are warranted to characterize the compounds responsible for the XO inhibitory activity of mushroom extracts.