Acquiring grammatical morphemes is the main part in language acquisition. Brown (1973), de Villiers and de Villiers (1973) and Larsen-Freeman (1975) mentioned that there is a natural order of acquisition of grammatical morphemes in English. This study investigates the development of acquisition of {-s pl.}, {-s ps}, and {-s 3d} by Iraqi EFL learners and to find out if Iraqi EFL learners follow the same order of acquisition. It is also to differentiate between male and female learners in their acquisition. The study was based on a grammaticality judgment test that was administered for 30 participants each academic year specifically in May 2013, 2014, 2015 and 2016 respectively. The results of analysis present the average of the percentage of identification of grammatical morphemes concerned. The average displays that the acquisition of {-s 3d} more fulfilled, with an average (66.583%), than {-s pl.}, {-s ps} which are (58.083%) and (50.25%) respectively. Also the results show that Iraqi male and female learners have the same order of acquisition of grammatical morphemes but there is a difference in the averages obtained which reveals that Iraqi female EFL learners acquire these 1 {-s pl.}: noun plural, {-s ps}: noun possessive, {-s 3d}: present third-person (Stageberg, 1981:92) grammatical morphemes better than male.