Nosema sp. is recorded in Saudi Arabia for the first time, in adult Apis mellifera collected from apiaries in Riyadh city. Samples of 100 workers were collected and examined for the infection with Nosema sp. 5% of the bees were found positively infected with Nosema sp. Spores were oval to elliptical shaped and measuring 6.4 (5.0–7.0) μm in length, 3.4 (3.0–4.5) μm in width. The conclusive identification of the present Nosema species will preclude until further ultrastructure and molecular studies. The present study concluded that intensive surveys are prerequisite to identify the species of Nosema and to estimate their distribution and prevalence in different regions of Saudi Arabia.