Allergic bronchopulmonary aspergillosis (ABPA), which requires a set of criteria for diagnosis, occurs in atopic individuals, predominantly asthmatics. Oral corticosteroids are the cornerstone for the management of the disease. Allergic Aspergillus sinusitis (AAS), clinico-pathologically similar to ABPA, is also diagnosed with a set of criteria including demonstration of fungal elements in sinus material. Heterogeneous densities on computed tomography of the para-nasal sinuses are caused by the 'allergic mucin' in the sinuses. A combination of oral corticosteroids and surgical removal of impacted sinus mucin is the current approach to treatment. Despite common clinico-immunopathological characteristics, the co-occurrence of both these diseases is a rarely reported phenomenon. This could be due to the fact that the two diseases are often encountered by different specialities. Screening all asthmatics for Aspergillus sensitisation could identify those with severe disease and those at risk for developing ABPA. AAS must be excluded in all patients with ABPA and vice-versa.