Impairment of cognitive functions is well recognized in patients diagnosed with multiple sclerosis (MS), especially those with a chronic progressive course. In fact, MS has been considered a type of "subcortical dementia" in which cognitive and behavioral abnormalities resemble those observed in patients with frontal lobe syndrome. Patients with frontal lobe syndrome are known to exhibit diverse cognitive and behavioral abnormalities which include, among others, diminished spontaneity of speech with difficulties producing appropriate words and phrases. It has been reported recently that extracranial application of extremely weak electromagnetic fields (EMF) in the picotesla range produced improvement in motor and cognitive functions in patients with MS. The present report concerns three women with MS (mean age: 44.3 +/- 8.5 yrs; mean duration of illness: 18.3 +/- 3.5 yrs), two with chronic progressive course and the third with a relapsing-remitting course in whom the Thurstone Word-Fluency Test, a reputed test of frontal lobe function, was administered prior to and following a series of 4 to 5 treatment sessions with EMF. Prior to the initiation of treatment with EMF all patients demonstrated word fluency performance which was well below age and sex-matched normal controls of similar level of education (mean output of MS patients was 42.6 +/- 1.1 words vs. 79.0 +/- 6.2 words of the controls). A series of treatments with EMF produced a 100% increase in word output within a short period of time (mean: 83.3 +/- 14.0 words). These findings suggest that this treatment modality improves frontal lobe functions in patients with MS and corroborate previous reports indicating beneficial effects of EMF on cognitive functions in these patients.