This single-center study aimed to evaluate relationship between the platelets count (PLT) and the degree of synovial perfusion in patients with high disease activity of arthritis. Conducted at the Department of Early Arthritis Clinic in National Institute of Geriatrics, Rheumatology, and Rehabilitation in Warsaw, Poland. The study enrolled 60 patients diagnosed with rheumatoid arthritis (RA) and group of 20 patients with psoriasis arthritis (PsA). Different laboratory variables were assessed and particularly PLT, disease activity was assessed by DAS 28(ESR) and simplified disease activity index (SDAI). The degree of the synovial membrane vascularization was assessed using power doppler ultrasound (PDUS) and additionally vascularity index was measured by PDUS index (INDEX%) in the region of interest (ROI). Statistical analysis was performed using Prism 9.0 software package (GraphPad Software, Inc., USA). No significant correlation was observed between PLT and INDEX% synovial vascularity, which may indicate that PLT has no influence on microvascular changes in the synovium and its PDUS assessment in RA and PsA patients.