The research goal was to identify the characteristics of grammar comprehension abilities in preschool children and to investigate whether certain factors impact the level of acquisition of grammar knowledge among these children. The research was conducted on a sample of 102 children (56 boys and 46 girls), age 4-6. For the purpose of this research, the children were grouped in four groups, with a five-month age interval among them. The Test for the Reception of Grammar (TROG) was used for assessing the acquisition of grammar knowledge. The research results indicate that there are statistically significant differences in the level of acquisition of grammatical abilities relative to children's age (F (3.98)=5.48; p=0.002; ƞ2 =0.14). By analysing the obtained data, we identified statistically significant differences in the achievement on applied tasks between the youngest group of children and other groups, where older children had higher scores (p<0.05). On the other hand, no statistically significant differences were identified between boys and girls in terms of achievement (t (100)=-0.968; p=0.335; d=0.22). Contrary to our expectations, no statistically significant differences were observed in the summary score on TROG test relative to mothers' level of education. The research results show that statistically significant differences are present only in the level of achievement of the children whose mothers have high school or college education, to the advantage of mothers with college education (p=0.009). More significant results were obtained in the same variable, where fathers' education is viewed as an impact (F (3.98)=2.90, p=0.039, ƞ2=0.081).