Objective: To determine the relationship between serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) with active disease in patients with juvenile rheumatoid arthritis (JRA). Methods: This is a cross-sectional analytical study conducted at the Department of Paediatrics, Abbasi Shaheed Hospital, Karachi for one-year duration from April 2020 to April 2021. All patients who met the MJA’s American College of Rheumatology (ACR) criteria were enrolled in the study. The ACR 20 improvement criteria were used to define the pardon of the disease, and those who met the ACR20 recovery criteria were included in the remission group. Laboratory tests such as PCR and ESR. Statistical analysis was performed using SAS software (version 10.3). Results: The study involved 90 patients, including 28 in the remission group (31.2%) and 62(68.88%) in the active disease group. There were 61.11% (n = 55) of females, and the ratio of males to females was 3: 4. The mean age of the subjects was 10.12 ± 3.39 years (4–17 years). Distribution of the age of admission by different subgroups, 13 patients (14.44%) aged 1-5 years, 31 patients (34.44%) aged 5-10 years, 40 patients (44.44%) aged 10-15 years and 6 patients (6.66%) were over 15 years old. The mean duration of the disease was 2.40 + 2.11 years (range = 0.3–7 years). The onset of the disease in 21 patients (23.33%) lasting one year (22.9%) from the onset of the disease, 48 patients (53.33%) presented one to five years from the onset of the disease, and 21 patients (23.33%) over five years. The most common type of arthritis was polyarthritis in 43 patients (47.77%), followed by oligo-arthritis in 31 patients (34.44%) and systemic onset in 12 patients (13.33%). The mean ESR was 41.03 + 27.80 mm / hour 1. (Range = 07-128 mm / hour 1) And mean CRP 16.1 + 13.80 mg / L (range = 6-47 mg / L). While the ESR was> 30 mm / 1 hour in 50 of the 90 patients (55.55%), 43 of these 50 patients (86%) were in the active disease group. Similarly, positive CRP was found in 58 patients (64.44%), of whom 52 (89.7%) belonged to the group with active disease. Compared with the remission and active disease groups, 33 patients of active diseases were female. In the active disease group, the mean age was 11.01 + 3.30 years, and the duration of the disease began at one year in patients. Polyarthritis was detected in 26/62 (41.9%) of patients in the active disease group. Conclusion: High CRP and ESR parameters are good for predicting active disease in JRA patients. Keywords: C-reactive protein, Juvenile rheumatoid arthritis, JRA and Erythrocyte mentation rate.