Introduction: Antimicrobial resistance has become one of the biggest threats to public health in the 21st century. Irrational and excessive use of antibiotics contributes to maintaining and increasing resistance. The opportunistic pathogen Pseudomonas aeruginosa causes mostly nosocomial infections and it is resistant to many antibiotics available on the market today. With the arrival of the Covid-19 pandemic, the structure of hospitalized patients as well as the consumption of antibiotics is changing which comes into question whether and to what extent resistance to existing antimicrobial agents in decreasing or increasing. Aim: to assess whether there has been an increase or decrease in Pseudomonas aeruginosa resistance since the appearance of Covid-19 infection compared to the pre-pandemic period and to analyze the reasons for this trend. Methods: The sample used are the existing laboratory findings of patients from 2018, 2019 and 2020 with isolates of Psedomonas aeruginosa from blood and cerebrospinal fluid samples at the Clinical Hospital for Infectious Diseases " Dr. Fran Mihaljević". The described data were taken in the period from January 2018 to December 2020. Data are presented using descriptive statistics. Antibiotic resistance is also shown graphically using relative frequencies. Resistance rates for all antibiotics are shown for each year. Also, for each used antibiotic, the resistance rate over the years is shown separately during trial period of 3 years. Results: A total of 54 samples were analyzed. The male elderly man population predominates. The most significant increase in resistance was observed in the group of ß-lactam antibiotics ( carbapenems and cephalosporin antibiotics). Also an antibiotic from the fluoroquinolone group showed a significant increase in resistance. It is noticeable that with the onset of the SARS-Cov-2 virus pandemic, the resistance of most antibiotics decreases, which is understandable due to reduced consumption of antimicrobial drugs and changes in the structure of hospitalized patients. The two new antipsudomass antibiotics ceftazidime-avibactam and ceftozolan tazobactam have been shown to be the best choice in the treatment of Pseudomonas aeruginosa. Conclusion: Pseudomonas aeruginosa is the leading cause of nosocomial infections and as such affects patients with a weakened immune response. The incidence rate of resistance to more and more drugs is constantly increasing, especially around the world, especially when we speak about carbapenems. Priority should be given to education of the medical professionals as well as wider population on the rational use of antibiotics and measures to prevent nosocomial infections. Multidrug-resistant Pseudomonas aeruginosa often leads to a poorer clinical outcome due to limitations in the use of effective antimicrobial agents, so there is an urgent need to harmonize medical and scientific communities to devise new treatmen strategies.