An abrupt antimicrobial resistance increase among Streptococcus pneumoniae strains has become a serious therapeutic problem in the recent years. The aim of this study was to describe the resistance increase of S. pneumoniae strains isolated in the West Pomerania Province over three years (2001-2003). Using E-tests method and NCCLS criteria for 80 pneumococal resistant strains the resistance degrees and patterns have been determined and analyzed in connection with their clinical origin. The majority of specimens of resistant strains isolated came from nasopharynx (80% strains) of infected ambulatory patients (81.3%), from children at nursery school age (65.7%), suffering from chronic upper respiratory tracts infection (86.7%). However, strains originated from older patients, hospitalized, in serious health condition showed higher resistance degrees. The greatest number of isolates (27.5%) showed resistance to 3 out of 9 tested drugs and over a half (53.8%) of the tested strains belonged to MDR strains, with increasing percentage over time: from 62.5% in 2001 to 69.8% in 2003. Resistance to 8 out of 9 determined antibiotics (except vancomycin) has occurred and domination of 4 resistance patterns: ELTS, S, TSH, PSI, present in 50.1% of the tested strains was observed. The phenomena observed in the study: growing resistance degree, increasing amount of MDR strains, emergence of new resistance patterns, testify to gradual pneumococcal resistance increase and give a picture of local trends in antibiotic therapy. Also the epidemiological data concerning patients, from whom the tested strains were isolated are adequate to risk factors of infection with resistant pneumococci.