Fungal spores are biological molecules that are widespread in the indoor and outdoor air. Several types of the very common fungal spores are known as allergens, with the potential to cause respiratory illnesses by increasing the aggravation of asthma and rhinitis. From January to December 2018, a cross-sectional environmental survey was performed to determine the dust fungal spore concentration in four district of Al-Najaf governorates and examine the potential correlation between the concentration of fungal spores and the numbers of patients have asthma, also the effect of some demographical characteristic on the percentage of asthma. Fungal spores in dust were collected using Achudume method, the samples were cultured at room temperature for 7-10 days, the identification and counting of fungi were performed. The data of patients have asthma was obtained from statistics division at hospitals and health centers located in these districts. The result of this study revealed the highest fungal spore concentration was in the dust of Kufa district (29%), moreover, the most prevalent fungal isolate from the dust belonged to the genus Aspergillus, Alternaria, Cladosporium, and Penicillium. There was a remarkable difference among the four districts regarding the type and concentration of fungal spores. There was a significant positive correlation between the number of patients have asthma and the concentration of fungal spores in dust (r_p= 0.96, p-value = 0.0001). The overall percentage of asthma in the study population was 4.1%, the rate of asthma appear to be more prevalent among male than female (2.47% vs 1,67%), there was no difference between the percentage of asthma in urban and rural areas (2.2%, 1.9%), and it was statistically non-significant at £ 0.05. There was a medium direct correlation between age groups and asthma (r_p= 0.687) towered the increase in age, but it was not statistically significant (P= 0.132). It was clear that most of the recorded fungal spore type have allergenic properties, which mean that increase their concentration in the environment of AL-Najaf can negatively effect on the status of patients have asthma.