OBJECTIVES:  The Pareto principle (or the “80-20 rule”) states than in many events, 80% of the effects come from 20% of the causes. The aim of the present study is to examine the application of the 80-20 rule to the Greek healthcare utilization across primary and secondary health care services. METHODS:  The participants of a National Survey conducted by the Greek National School of Public Health (≥18 y/o) in 2015 that used either primary or secondary healthcare services were included in the analysis. The sample consisted of 2012 people, 936 of whom used health care services. Utilization of primary healthcare was estimated by the number of consultations in primary health care services, while utilization of secondary health care was estimated by the number of hospital admissions in a twelve month period. RESULTS:  Users of healthcare services had an average of 2.48 primary healthcare consultations per person for preventive examinations, 2.35 for transient illnesses, 6.00 for chronic diseases, 6.10 for prescribing, 2.64 for laboratory tests and 1.51 hospital admissions per year. Application of the 80-20 rule revealed that 80% of primary health care consultations for preventive examinations, transient illnesses, chronic diseases, prescribing and laboratory tests were accounted for by 45%, 31.6%, 26.8% 37.3% and 41.3% of all users of primary health care services respectively, while 80% of hospital admissions were accounted for by 18.7% of all users of secondary healthcare services. CONCLUSIONS: This study provides a description of healthcare utilization with application of the 80-20 rule and suggests that a small number of patients is responsible for the majority of primary healthcare consultations and hospital admissions. Chronic diseases and multimorbidity are the main variables which increase healthcare utilization. Targeted interventions and an improvement in the management of chronic diseases could lead to a reduction in hospital admissions.