Both the seasonal and diurnal incidence of grass pollen in the atmosphere of Melbourne have been established using data from seven pollen seasons (1975–1980 and 1991–1993). Grass pollen represented an average of 26% (ranging from 22 to 33.1%) of the total pollen count. November and December are the most important months with an average of 81% of the total grass pollen. There is marked variation in the total seasonal and daily grass pollen counts. The total seasonal grass pollen count varied from 2319 to 6798 grains, while the daily grass pollen count fluctuated from 0 to 549 grains m-3of air. In this study, we arbitrarily assigned days during the grass pollen season with > 100 grains m-3of air as extremely high, > 50 grains m-3of air as high, 21–50 grains m-3of air as moderate and < 20 grains m-3of air as low. The number of days with extremely high counts varied from 3 to 26. The number of days with high counts varied from 7 to 21, with the highest number of days occurring in seasons with more than 5500 grass pollen. This classification has been used in the dissemination of pollen counts to the media in order to provide information for allergy suffers.