Giardia spp. is the most common intestinal protozoan (causing gastrointestinal illness) and the most frequentcause of parasitic gastroenteritis in humans and animals worldwide. The aim of this study was to highlightnew data in a specific area regarding clinical presentation and epidemiological prevalence over a long periodof time. Patients (a total number of 54,623 patients) admitted in a tertiary center for infectious diseases servinga county for a period of 14 years were tested for infection with Giardia. Positive cases were recorded through analyzing the clinical complaints, the month of incidence and the demographic area from which the patients camefrom. Longitudinal trends have been evaluated. The incidence of giardiasis among the tested patients was 4.47%.A decreasing trend was observed regarding the annual incidence. Patients between the ages of 15 and 44 presented most commonly giardiasis, especially those from urban areas and women. The most common symptomsare loss of appetite (71.24%) and abdominal pain (69.07%). The highest monthly incidence was quoted in July(10.65%), August (10.49%) and June (10.20%). This epidemiological study allows a better knowledge of the infection with Giardia spp. It gives the long-term changes in demographic characteristics of the infected patients in aspecific area and the monthly incidence.