The aim of this research is to examine the effect of gender and developmental periods of the Turkish students on their aggression tendencies. The universe of the study is comprised by the Turkish students. In selecting a sampling unit, the method of criterion sampling, one of the types of purposeful sampling has been used. Pursuant hereto, the conditions; that these studies have been carried out in the period of 2004-2005 on children, adolescents and young-adult students, that the validity and reliability studies of the measuring instrument have been presented, that the references for obtaining them were from the published sources of  theses and articles, and that the arithmetic mean, standard deviation and sampling amounts were given, have duly been sought.  For the collection of data; Ulakbim, EbscoHost, Eric, thesis center of Higher Education Institution (YÖK) and the databases of Google’s Scholar, have been utilized. Sample size is comprised by an amount of 25642 students (12621 female and 13021 male students).

In analyzing the data, the software program of Comprehensive Meta Analysis (CMA) has been benefited from and an amount of 47 studies matching the criteria have been looked through. The confidence interval has been taken as 0.05. The magnitude of the general effect has been revealed with the g coefficient of Hedges from the point of view of the variable of gender. Value of the general effect has been examined from the point of view of the magnitudes of effects of the; developmental periods, which is one of moderator variables (childhood, adolescence and young adult), type of study (article and thesis) and years of the study. In examining the biasness of publication, the statistics of funnel pot and Kendall have been made use of. In calculating the value of influence, the model of random effects has been used.

It has been observed in the study that the general aggression scores have low level of the effect of significance on genders. The magnitude of the effect of the aggression scores on males has been found out to be at lower level (ED=0.19) and at relatively higher level compared to females (ED=0.10). The magnitude of the effect of the period of adolescence, which is one of the variables of the moderator, has been observed as the variable that has the highest effect (ED=0.42) at medium level. It was found that, the theses create a relatively lower level of effect (ED=0.16) compared to the articles.  Also, it has been observed that, according to years, the magniude of the effect of the aggression scores has shown an increase at significant level. In conclusion, it can be said that, from the statistical point of view, the general aggression scores have the magnitude of effect on males and adolescence at significant level.