Records from patients admitted to the surgical or medical department or examined in the respective outpatient departments in a Kuwaiti district hospital were reviewed retrospectively to discern the demographic characteristics of patients with complicated urinary tract infections (UTI), underlying conditions, pathogens and their antimicrobial susceptibility patterns. Kuwaiti nationals constituted the largest group, followed by Egyptians, which in the population of 225 patients studied comprised 41% and 27%, respectively; 65 of these 225 patients (29%) had urinary stones; 33 of the 92 Kuwaiti patients (36%) had diabetes mellitus; 38 of the 60 Egyptian patients (63%) had urinary stones and 18 had bilharziasis (30%). Pathogens were isolated 353 times from 225 patients. Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and several other organisms in those patients with bilharziasis, urinary stones, and especially diabetes mellitus, displayed lower susceptibility frequencies to antimicrobials in comparison with other surgical and medical UTI isolates. Surgical and medical UTI organisms showed an overall higher antimicrobial resistance frequency than did UTI organisms from the maternity department or regional clinics. More than half of the population of Kuwaiti consists of expatriates from different countries. Such a population structure can exhibit peculiarities when health is considered. All this should be taken into consideration while dealing with disease management.