In a large multicenter randomized, and double blind placebo controlled trial of glatiramer acetate (GA) in primary progressive multiple sclerosis (PPMS), an originally unplanned post hoc analysis suggested that males assigned to GA therapy experienced less progression of disability than their counterparts assigned to placebo; no similar potential treatment differences were seen among the females in this study. In this report we further explore the data from that trial in an attempt to determine if this outcome could have been the expression of a gender dependant treatment effect. The analyses conducted do not support a treatment by gender interaction for GA in either PPMS or relapsing forms of MS. Nor could we find consistent precedence in the literature for important effects of gender on outcome, recognizing that such effects have not always been carefully sought. It remains reasonable to consider that there exist differences in the rates of clinical disease progression between men and women with MS that should be better studied.