Objective To investigate the changes of the pulmonary surfactant protein-D (SP-D) in serum and cerebrospi-nal lfuid in children with viral encephalitis (VE). Methods The levels of SP-D in serum and cerebrospinal lfuid were detected by a double-antibody sandwich enzyme-linked immunosorbent assay and compared in thirty children with VE in acute and con-valescent phases and in 12 children without VE. Results The levels of SP-D in serum and cerebrospinal lfuid between groups of VE acute phase and convalescent phase and no VE were statistically signiifcant (F=103.58,118.15, all P<0.01). The levels of SP-D in serum and cerebrospinal lfuid in children with VE in acute phase and in convalescent phase were signiifcantly lower than children without VE (P<0.01). The levels of SP-D in serum and cerebrospinal lfuid in children with VE in convalescent phase were all signiifcantly higher than those in acute phase (P<0.01). In children with VE, the level of SP-D in cerebrospinal lfuid was weakly correlated negatively with the count of nucleated cells. Conclusions SP-D might be involved in the pathogenesis in VE. The detection of SP-D in serum and cerebrospinal lfuid has a certain value for diagnosis of VE.