Objective To study the changes and significance of serum hydrogen sulfide (H2S) levels in childrenwith benign infantile convulsions associated with mild gastroenteritis (BICE). Methods Forty-two hospitalized childrendiagnosed with BICE were recruited to the observation group, and 46 children admitted due to acute gastroenteritis alonewere recruited to the control group. Serum H2S levels were measured by a spectrophotometer. Results The serumH2S level in the observation group was significantly lower than in the control group (28±12 μmol/L vs 45±10 μmol/L; P<0.01). The patients with a number of convulsions greater than or equal to two had significantly lower serum H2Slevels than those with a number less than two (P<0.05). The number of convulsions was negatively correlated withserum H2S level in BICE patients (r=-0.485, P=0.001). When a convulsion exceeded 5 minues in duration, the durationwas negatively correlated with serum H2S level (r=-0.736, P=0.004). Conclusions The reduction in endogenous H2S level might be one of the causes of convulsions in BICE patients. The degree of reduction in H2S level is associated withthe number of convulsions and the duration of convulsion (when it exceeds 5 minues). Further investigation is needed todetermine the clinical significance of these results.