Well-preserved Permian radiolarians have been discovered from chert blocks embedded in a unit in the Pai district, Mae Hong Son province, northwestern Thailand that was recently mapped as Carboniferous. Twenty-four taxa belonging to ten genera have been recognized and some significant forms of Follicucullus are present. Two upper Maokouan (Capitanian) to lower Wuchiapingian radiolarian assemblages (Follicucullus monacanthus, Follicucullus charveti - F. porrectus assemblages) are reported. Follicucullus charveti CARIDROIT & DE WEVER is interpreted as a possible provincialism rather than being endemic like other members of the same genus. These results provide more data to demonstrate that in northern Thailand, the Devonian to Triassic was of a zone of deep siliceous marine sedimentation. The resultant deposits are one of the longest witnesses of continuous deposition in an oceanic setting.