The studied Acetylcholine receptor antibody (AChR Ab) in 92 patients diagnosed myasthenia gravis, AChR Ab assay was done by Enzyme-linked Immunosorbent assays - ELISA technique and reported by titer in nmole/L. The positive result was defined by titer or = 0.52nmole/L. In the myasthenia gravis group, with age mean of 45 years old. The female: male ratio was 1.96:1. All of the patients at the time of presentation were in group I, lIa and lIb of clinical grades of Osserman's classification. AChR Ab-positive results in 84 out of 92 patients (91.30 percent). In the control group, tests were all negative. The results of the test made the sensitivity of 91.30 percent and specificity of 100 percent. The positive predictive value was 100 percent, the negative predictive value was 78.94 percent, There was no relative between AChR Ab titer and clinical features. This test is a very valuable In the definitive diagnosis of myasthenia gravis.