Background. Around 10 - 15% of patients with myasthenia gravis (MG) have a thymoma, and non-motor symptoms are more frequent in these patients. We hypothesised that neuropsychiatric symptoms would also be more frequent. Methods. A cross-sectional study of 30 consecutive MG patients attending a clinic at Groote Schuur Hospital, Cape Town, South Africa, was done over a 6-month period in 2010. Each patient underwent a series of single-blinded neuropsychiatric assessments, including the 16-item, self-reported Flanagan Quality of Life (QOL) scale, the Beck Depression Inventory second version, the Young Mania Rating Scale, the Hamilton Anxiety Rating Scale and the Brief Psychiatric Rating Scale (BPRS). Results. The frequency and nature of neuropsychiatric symptoms were similar between thymoma (n=9) and non-thymoma (n=21) MG patients. Symptoms of moderate or severe depression and anxiety were present in around 30%. The severity of depression symptoms correlated with MG severity. Prednisone dosing was not associated with neuropsychiatric symptoms or QOL scores. Those with longer duration of MG were more likely to have higher scores on the BPRS and anxiety scales. Those with younger-onset MG had higher BPRS scores and a tendency to suicidal behaviour. Conclusion. Although no association with thyoma was found, this study shows that neuropsychiatric conditions may be underdiagnosed in patients with MG. Systematic depression screening should be done at outpatient clinics, particularly for those who developed symptoms at a young age, those with severe disease and those with a long duration of illness.