Objective: To determine the clinical and laboratory features during the disease course in patients of anti cytoplasmic antibody (ANCA) associated vasculitis in Pakistani patients presenting to a tertiary care center. Study Design: Case series. Place and Duration of Study: Fatima Memorial Hospital Shadman Lahore, from Dec 2018 to Mar 2019. Methodology: A collection of 20 patients regarding demographic data, constitutional symptoms, mucocutaneous symptoms and signs, upper respiratory symptoms, lower respiratory symptoms, orbital and ocular manifestation, cardiovascular, peripheral vascular manifestation, central and peripheral neurologic manifestation, abdominal manifestation and renal manifestation Results: Sixteen patients (80%) had a diagnosis of Granulomatosis with Polyangiitis, and 4 patients (20%) were of microscopic polyangiitis. The most common systemic involvement in descending order were constitutional symptoms (75%), ear nose and throat symptoms (50%), renal (50%), respiratory (45%), ocular (40%) and neurologic (40%). Most common laboratory abnormalities in our patients included leukocytosis (45%), anemia (35%), hematuria (50%), proteinuria (45%), and elevated serum creatinine (45%). Cytoplasmic-anti cytoplasmic antibody (C-ANCA) was positive in 11 (55%), all cases were of granulomatosis with polyangiitis, P-ANCA was positive in 5 (25%) of all patients, with 4 (100%) in Microscopic polyangiitis. Analysis of Granulomatosis with Polyangiitis according to gender and cytoplasmic-anti cytoplasmic antibody status showed correlation of renal involvement with cytoplasmic-anti cytoplasmic antibody status with statistical significance of p=0.036. Plain chest X-rays showed infiltrates in 2 (10%), nodularity 2 (10%), cavitation in 2 (10%), effusion in 1 (5%), and reticulonodular showing in 1 (5%) patients. High-resolution computed tomography findings included ground-glass opacification in 5 (25%) and Cavitatory lesions in 4 (20%). Conclusion: Granulomatosis with polyangiitis was found to be the more prevalent form of anti cytoplasmic antibody associated vasculitis in our population, with upper respiratory, lower respiratory ocular and neurologic symptoms being the common manifestations. A significant proportion of granulomatosis with polyangiitis is anti cytoplasmic antibody negative, with renal involvement being its common manifestation. [ABSTRACT FROM AUTHOR]