OBJECTIVE: To assess the relationship between diurnal temperature range (DTR) and sudden infant death (SID) between 2001 and 2004 in Shanghai, China. METHODS: We conducted a time-stratified case-crossover analysis to estimate the percent increase of SID associated with changes in DTR after adjustment for daily weather conditions (temperature and relative humidity) and outdoor air pollution. RESULTS: DTR was significantly associated with daily SID. An increase of 1 degrees C in the current-day (L0) and in the 2-day moving average (L01) DTR corresponds to a 1.56% (95% CI: 0.97%, 2.15%) and a 1.89% (95% CI: 1.17%, 2.60%) increase in SID, respectively. CONCLUSION: An increased DTR was associated with an increased risk of SID in Shanghai. More studies are needed to understand the effect of DTR on infant deaths.