Background:Rheumatic diseases are referred to as conditions affecting joints, muscles, ligaments, tendons, and bones. According to a report by World Health Organization, rheumatic and musculoskeletal diseases were labeled as the second most reported cause of disability around the globe. The purpose of this study was to estimate the prevalence of rheumatic diseases in a tertiary care hospital of Karachi; additionally, associations with age groups, gender and comorbidities were obtained as well.Methods:A cross-sectional study was conducted at the Orthopedic Out Patient Department (OPD) of Dr. Ruth KM Pfau Civil Hospital, Karachi over a span of three months in 2018 (February till May). All 346 patients were follow-up diagnosed cases in the age range of 11-90 years, divided into groups of adolescents, young adults, adults, and older adults. The subjects were questioned about their symptoms, duration of illness, presence of comorbidities, genetic background and the therapy they are undergoing along with compliance. Simple statistical analysis of frequency was done, whereas chi-square test was applied to study associations with gender, age groups, and comorbidities.Results:During the study period, a total of 2000 patients visited the orthopedic OPD, 346 of which were diagnosed cases of rheumatic diseases, yielding a prevalence of 17.3%. The mean age of rheumatic patients who partook in the study was 46.15 ± 15.49 (Range: 12 – 84). Osteoarthritis was recorded as the most prevalent condition, followed by non-specific low back pain and rheumatoid arthritis. Osteoarthritis was statistically significant in young adults, adults, and older adults, while non-specific low back pain had significant associations with gender, young adults, and adults. Diabetes was significantly associated with osteoarthritis, non-specific low back pain, shoulder pain syndrome and psoriatic arthritis, while hypertension significantly co-existed with systemic lupus erthematosus.Conclusion:Rheumatic diseases constitute a major disease burden in almost all of the age groups, especially in young patients (18-40 years) within our setup.