The activity concentration of ¹³⁷Cs and ⁴⁰K and total K content in the sclerotia of the Chinese medicinal fungus Wolfiporia cocos collected mainly from Yunnan province of China during the period 2013–2015 were investigated. W. cocos in Yunnan is collected from the wild and is cultivated in field conditions and the wood substrate used is derived from the local pine (Pinus yunnanensis Franch.) logs from neighborhood forests. The outer part of sclerotia was found to be richer than the inner one in both ¹³⁷Cs and ⁴⁰K with median values of 7.3 and 3.2 Bq kg⁻¹ dry weight (dw) for ¹³⁷Cs, 220 and 140 Bq kg⁻¹ dw for ⁴⁰K. The median K concentrations were 6800 mg kg⁻¹ dw in the outer and 3700 mg kg⁻¹ dw in the inter parts. No statistically significant correlation was found for activity concentrations between the inner and outer parts, both for ¹³⁷Cs and ⁴⁰K (p > 0.05). Using the median activities of ¹³⁷Cs, the nominal values of effective dose (mSv) for exposed adults annually consuming 50 g of sclerotia, were estimated at 0.0035 mSv and 0.084 mSv (outer part), and 0.0020 mSv and 0.040 mSv (inner part) per capita, respectively. Sclerotia of W. cocos seemed to be a relatively good source of K.