Speaking English fluently and accurately is the most important, favorite, and complicated skill for EFL learners. The present study was an attempt to investigate the morphological speaking errors of Iranian EFL learners across proficiency levels and gender. To this end, a corpus of 1399 tokens of speech morphology errors was collected. The learners' oral production was observed and recorded naturally using various communicative tasks in class. The errors were then detected, transcribed, coded and classified following James (1998) taxonomy of errors. The results represented misselection as the most frequent type at morphology level. The results further showed significant difference between genders in terms of making grammar errors. The findings of this study can provide feedback for English teachers supervisors, and syllabus designers to help EFL learners develop their intrelanguage knowledge of grammar through revisiting teaching methods and implementing remedial materials.