Various studies have been conducted on the role of meteorological variables on the onset or complications of psychiatric disorders. For example low air pressure was directly related to violent crimes and suicide. As these relationships are not clear, we decided to devote this paper to the study of such factors.

The daily hospitalization rates of Ebn-e-Sina Hospital were extracted from the archive files. Also the daily rates of murder, suicide, and quarrels were obtained from the Legal Medicine Department. Meteorology data were taken out of the daily reports of the Meteorology Organization of Khorassan Province. The data were analyzed by statistical tests such as ANOVA and POST HOC.

In our statistical analysis, there was a significant statistical relationship between minimum daily temperature, maximum daily temperature, average daily temperature, minimum daily moisture, maximum daily moisture, minimum daily air pressure, and maximum daily air pressure and the number of quarrels and hospitalizations at Ebn-e-Sina Psychiatric Hospital during the year 2005 in Mashhad. Also, the statistical data indicated that no meteorological variable had any effect on the rates of murder and suicide in the city.

It will be useful to consider meteorological variables in preventing the onset, complications and treatment of psychiatric disorders. Yet there was no relationship with the rates of murder and suicide. As the number of murder and suicide is low during one year it is recommended the study carry out in longer period.