An experimental allergic encephalomyelitis was induced by bovine myelin basic protein (MBP) and bovine galactocerebroside (GC) on male guinea pigs. Animals were divided into five experimental and one control groups. Among the five experimental groups, three were inoculated with 75 micrograms, 150 micrograms and 300 micrograms of MBP, respectively, to see the dose dependency of demyelination. The fourth group was inoculated with mixture of 75 micrograms of MBP and 180 micrograms of GC and the fifth group with 180 micrograms GC. All inocula was injected intradermally in emulsion state mixed with equal amount of complete Freund adjuvant. Control group was injected with adjuvant only. Clinical symptoms began to appear from 15th day after inoculation and animals were sacrificed on maximum neurologic deficit or 4 to 5 days after the onset of symptoms. Demyelination was observed in 6 out of 8 animals inoculated with MBP/GC mixture, while only 3 out of 24 animals inoculated with various dosage of MBP showed demyelination. The difference was statistically significant. Serum antibodies to MBP and GC were measured by ELISA method. All of the eight animals inoculated with MBP/GC mixture and two animals inoculated with GC had low titer of anti-GC antibodies, while all animals inoculated with MBP, MBP alone or MBP/GC mixture, had high titer of anti-MBP antibodies. Therefor it is concluded that the demyelination is augmented by GC and is not significantly dose-dependent on MBP.