Spore concentration profiles along a vertical line passing through and above a growing sugarcane crop were studied using a suction-line apparatus. Two tests were conducted at monthly intervals for about 8 months with a uniform set-up consisting of six miniature suction traps located at 4 ft apart from ground to 20 ft. The seasonal changes in the vertical profiles of smut spores, conidia ofCladosporium, Nigrospora, Lacellinopsis and total airspora are presented graphically on a log-log scale. Spore concentrations are always found to be greater within the crop than above and the variations in the shapes of profiles at any time in a day or in the season appear to be closely related to source height, crop height, availability of suitable substrate and the prevailing weather. The effects of abnormal weather conditions and the agronomic practices on spore profiles are also presented.