The most abundant volatile sulfur compound found in the surface layers of the central equatorial Pacific Ocean (148 ¿W to 170 ¿E) was dimethyl sulfide (DMS). Concentrations of DMS ranged from 100-400 ng DMS/L; the highest concentrations occurred at 2 ¿N and 148 ¿W. DMS accounted for more than 97% of the total volatile sulfur species present, and was significantly correlated with chlorophyll 'a'. Elevated concentrations of DMS near the equator are related to nutrient eutrophication stimulated by equatorial upwelling and the horizontal transport from the east. Vertical profiles taken at 9 stations indicated that maximum DMS concentration occurred at 20-40 m, with concentrations decreasing to <1 ng DMS/L at 150-200 m. Flux calculations indicate that the central equatorial Pacific (6 ¿N to 6 ¿S between 148 ¿W and 170 ¿E) supplies about 1.0 Tg DMS/yr, assuming a mean surface concentration of 200 ng DMS/L and a piston velocity of 2.3 m/d.