Aim of the study:
Personality is one of the most important factors affecting the treatment course of patients with psychiatric disorders. The present study aimed to find the possible relationship between personality factors and response to selective serotonin reuptake inhibitors treatment for major depression.

Subject or material and methods:
In the present prospective study, one hundred and seven patients with mild or moderate depression treated with citalopram, sertraline or fluoxetine for two months. Every patients were evaluated by Hamilton depression test (as pre-test and post-test) and Temperament and Character Inventory (as pre-test) and their response to treatment evaluated base on their Hamilton depression test. The collected data were analyzed using ANOVA, chi- square, Pearson's correlation coefficients tests and logistic regression.

Results:
The mean age of the patients was 39.7 years and most of the population were female (71.9%). The results showed that decrease in RD (OR=0.85, P=0.05) and age (OR=0.93, P=0.003), and increase in CO score (OR=1.32, P<0.001) had a significant effect on the likelihood of being responsive to the treatment.

Discussion:
The present study demonstrated that the cooperativeness could be considered as an appropriate predictor of treatment response among responders and non-responders. The investigation of four groups revealed that those with complete response had higher cooperativeness and lower novelty seeking while the non-responsive group had higher Persistence and self-transcendence.

Conclusions:
Temperament and character or at least some of their traits may predispose response to depression treatment.