Arabic dependency parsers perform poorly compared to parsers of other languages. There is little research on improving the performance of Arabic parsers. However, recent research has shown slight improvements in the performance of dependency parsers by utilizing the lexical level of a dependency treebank. To our knowledge, no previous study has studied the effect of utilizing the syntactic level. In this study, we empirically investigated the impact of varying the set of dependency relations on the performance of Arabic dependency parsers. The results were compared to those of previous studies, and showed that having an appropriate set of dependency relations could improve the performance of an Arabic dependency parser.