Recent research studies in several alphabetic orthographic systems have shown a significant contribution of morphological awareness in the development of spelling ability. It is assumed that awareness of morphemes facilitates the application of morphophonemic principles on spelling. However, apart from its effect on understanding the conventions of the general spelling system of a language, morphological awareness seems to facilitate the orthographic performance of specific morphemes as well, especially inflectional suffixes, through their morphemic differentiation. The aim of this longitudinal study was to examine the contribution of morphological awareness in Kindergarten and Grade 1, on children’s spelling ability of inflectional suffixes in both Grades 1 and 2. Two hundred and fifteen Greek – speaking children from Kindergarten up to Grade 1 were assessed on measures of: (a) morphological awareness (e.g., word analogy, decomposition of derivative words, reversing compounds), (b) general cognitive skills (nonverbal intelligence, verbal intelligence, short-term memory, vocabulary), and (c) early literacy skills (phonological awareness, rapid automatized naming, letter knowledge). Also, in both Grades 1 and 2 children were assessed on measures of spelling ability of inflectional suffixes in words and pseudowords. The results of the hierarchical regression analyses showed that the morphological awareness of children in both Kindergarten and Grade 1 predicted significantly their spelling of inflectional suffixes only in words, in Grades 1 and 2 respectively, beyond the effects of cognitive and language skills. Morphological awareness skills did not contribute significantly to children’s spelling of inflectional suffixes in pseudowords. Overall, these findings highlight that early morphological awareness skills contribute significantly to the development of spelling ability even at the early primary school years. Therefore, it is suggested that the teaching of spelling inflectional suffixes has to emphasize the semantic and syntactic role of inflectional suffixes through activities of writing rather than memorizing rules for the correct spelling of each inflectional suffix.