This study investigates the dynamics of the Greek General Private Clinics Sector from 2012 to 2020, focusing on the interplay between market concentration, measured by the Herfindahl-Hirschman Index (HHI), and key financial ratios including Return on Equity (ROE), Gross Profit Margin, Operating Profitability, Net Profit Margin, Earnings After Tax Margin, and Return on Assets. Over the study period, HHI exhibited a significant increase, indicating heightened market concentration within the sector. This rise in HHI correlated positively with Return on Equity (ROE) and Operating Profitability (OP), suggesting that higher market concentration tended to coincide with improved financial performance. Unexpected variations in HHI during certain years underscored the sector's adaptability to market dynamics, revealing insights into how changes in market structure influence financial outcomes within the Greek private clinic industry. Keywords: Greek Healthcare, Market Concentration, Financial Ratios, Herfindahl-Hirschman Index (HHI), General Private Clinics, Financial Analysis.