Background: Evidence for extreme ambient temperature effects on the risk of mental disorders (MDs) is limited. In this study, we evaluated the short-term effects of daily mean temperature on hospital admissions of MDs in Shanghai, China. Methods: We obtained daily hospital admission data for MDs, daily meteorological and ambient pollution data in Shanghai from January 2008 to December 2015. Adjusted for time trend, air pollution, relative humidity and other confounders, a quasi-Poisson generalized additive model (GAM) combined with a distributed lag non-linear model (DLNM) was used to analyze the lag-exposure-response relationship between daily mean temperature and hospital admissions for MDs. Results: Total daily hospital admissions for MDs during the study period were 93,971. With a reference of median temperature (18.3 degrees C), there was a significant positive association between the temperature above threshold (24.6 degrees C) and MD hospital admission visits at a lag of 0-1 days. The relative risks of extreme hot temperatures (33.1 degrees C, 99% percentile) over the lag 0-1 days compared to median temperature were 1.266 (95% confidence intervals: 1.074-1.493). No effect of cold weather on the hospital admissions for MDs was observed. Conclusions: This study suggests that extreme hot temperature poses significant risks on MD; health counseling and cooling measures should be considered for the susceptible population. (C) 2017 Elsevier B.V. All rights reserved.