PURPOSE: to check the influence of age on the lexical and grammatical performance, and investigate the correlation between the number of usual verbal description in expressive vocabulary test and measures for mean length of utterance in children with Specific Language Impairment. METHOD: thirty children with Specific Language Impairment between 4:0 and 6:11 year-old took part in the study, and ten were selected from each age range that had the Expressive Vocabulary Test (ABFW) and Mean Length of Utterance Test, independent gender or education. The study was retrospective, based on filming and recordings of those tests as for the data collection. RESULTS: no statistical difference was found in the grammatical performance among ages, but positive correlation was observed among the usual verbal description and parameters MG-2 and EME-P for Mean Length of Utterance Test (p< 0.05). CONCLUSION: age alone is not enough to predict improvement of vocabulary and grammar; however the expansion of nouns in vocabulary promotes the increase in the length of produced utterances and the use of grammar function words.