Air spora over groundnut fields at Visakhapatnam was studied for a period of one year, i.e., from 1st June 1974 to 31st May 1975, using a ‘hirst spore trap’ installed with its orifice at 0·5 m above the ground level. More than 60 fungal spore types, hyphal fragments, pollen grains, epidermal hairs, insect parts and other inorganic particles were observed on the exposed trap slides. Seasonal and diurnal periodicities and per cent contributions to the total air spora were recorded for 38 components.Cladosporium was the most dominant spore type contributing 47·32% to total air spora. Basidiospore and ascospore types occurred mainly during rainy season while most of the conidial types occurred in high numbers during winter. Ascospores, basidiospores, conidia ofFusariutn and insect parts showed night peaks while most of the conidial types had peaks around noon. Based on the diurnal peak hour different spore types were grouped into eight types. Some spore types showed marked seasonal variations in their diurnal periodicity pattern. Most of the conidial types occurred in higher numbers when the temperatures were in the range of 28–33° C and relative humidities of 60–75%. Rain had a profound effect on the air spora.