To investigate whether the prevalence GSTT1 and GSTM1 deletion genotypes (T0M1, T1M0 and T0M0) are increased in certain spontaneous optic neuropathies.We compared the prevalence of GSTT1 and GSTM1 deletion genotypes in 108 Arab patients with optic neuritis (ON, 26 patients), LHON-like optic neuropathy (LLON, 35 patients), sporadic bilateral optic neuropathy in children (SBON, 21 patients) and non-arteritic ischaemic optic neuropathy (NAION, 26 patients) to 120 ethnicity-matched controls. Genotypes were determined by multiplex polymerase chain reaction.All three GST deletion genotypes were significantly more prevalent in the entire optic neuropathy group than in controls. When patients were stratified by optic neuropathy type, the prevalence of at least one deletion genotype was significantly increased in each type of optic neuropathy.These results imply that GST malfunction in the setting of GST deletion genotypes may interfere with metabolism of oxidative intermediates and may exacerbate direct or indirect pathological effects of oxidative stress on the optic nerve in the setting of these spontaneous optic neuropathies. It is possible that these GST polymorphisms are risk factors for the types of optic neuropathies investigated here.