This research aims to describe and compare lexic and syntax of three primers intended learning croatian language and approved by Ministry of science, education and sport in Croatia. Primers were analized on two level of analysis, lexical and syntactic level. The purpose and contribution of low frequency words in text-books for beginning reders has been discussed on lexical level of analysis. It is well-known that large number unknown words leads to lack of understanding the text along with the absence of the vocabulary growth which is considered as one of the purposes of primers. Sintax analysis was conducted to find out more about distribution of syntactic structures among primers. Many studys shows that childern are not capabale of understanding some subordinated clauses upon age of ten.That is why this researh is interested in their share among primers. Working memory span has influence on reading performace therefore mean lenght of utterance in words was calculated. Instructions for tasks performance, explanations of unknown words and author's comments were analyzed separately from texts and poems. Low frequency words were determined as those words that appeared less than twelve times. Program FREQ was used to calculate frequency of words and program MLU was used for calculation of the average lenght of sentance. Both programs are included in software package CLAN. Results of this research have shown that more than ninety percent of words in primers are low frequnced words. There were noted the appearances of words that are rare even in texts for adult readers. Syntactic analysis has shown that simple sentances are most common structures. Analysis aslo showed the different distribution of syntactic structures among primers. The average lenght of sentance does not exceeds the working memory span.