The use of the microbiology laboratory for the investigation of urinary symptoms and the test positivity rate for the urine specimens varies considerably. We used qualitative methods to explore how and why primary care staff make diagnostic and management decisions in patients presenting with urinary symptoms. Stratified random sampling was used to include general practitioner (GP) practices that were heavy and light users of the microbiology service. The data were analysed using a modified grounded theory approach utilising the constant comparative method. Frequent users of the laboratory, with low specimen positivity, did not use near patient tests (NPTs) and sent urines from most patients with urinary symptoms to confirm their clinical diagnosis. Frequent users with high positivity advise patients with negative NPTs and send all specimens with positive NPTs for antibiotic susceptibility testing. Infrequent users did not value the laboratory for diagnosis, made great use of NPTs, and tended to prescribe empirical antibiotic treatment even in patients with minimal symptoms. Guidance on the management of urinary symptoms, the use of near patient tests and laboratory culture should form part of the ongoing education of primary care staff.