BACKGROUND: Respiratory diseases are pathological conditions affecting the organs and tissues involved in gas exchange. Pulmonary function tests allow for the classification of the severity of respiratory diseases, their follow-up, and treatment response assessment. The aim was to determine the prevalence of chronic respiratory disease and the risk factors in Khartoum, Sudan. METHODS: A descriptive cross-sectional hospital-based study was conducted in the Respiratory Department from May to October 2021, including the patients who underwent pulmonary function tests. Data were analyzed using Statistical Package for Social Sciences, version 25.0. RESULTS: Out of the 396 study participants, 214 (54%) were above 40 years of age with similar gender distribution and a male-to-female ratio of 1.1: 1, and almost all were Sudanese. Clinically, 40.4% had normal body mass index (BMI), 24.2% underweight, and 13.6% were obese. Smokers represented 19.4% of the study participants. Moreover, 18.2% reported a positive history of bronchial asthma. Regarding pulmonary function test patterns, 50.8% exhibited normal results, 25.3% displayed restrictive patterns, 19.7% showed obstructive patterns, and 4.3% had mixed patterns. Chi-square cross-tabulation testing revealed a significant association between older ages of participants and the abnormal pulmonary function test results ( CONCLUSION: The study revealed that the proportion of respiratory diseases with abnormal lung function test results is considerable and should not be ignored, especially among older patients. Therefore, when indicated, attention should be paid to performing lung function tests widely to accurately identify the prevalence rates of lung diseases and associated risk factors in Sudan.