Surface nitric acid and particulate nitrate measurements were made in the equatorial Pacific region using impregnated filter techniques. The average HNO3 mixing ratio of 38 pptv is nearly ten times the average noonday NO mixing ratio measured simultaneously by McFarland, et al. The highest HNO3 values, 61 and 68 pptv, were measured when rain-showers were taking place in the vicinity of the sampler. Particulate NO3- concentrations ranged from 68 to 245 pptm