BackgroundHIV-infected patients often present to primary care several times with HIV-indicator conditions before diagnosis but the opportunity to test by healthcare professionals (HCPs) is frequently missed. Current HIV testing rates in primary care are low and educational interventions to facilitate HCPs to increase testing and awareness of HIV are needed.MethodWe implemented a pilot feasibility stepped-wedged randomised controlled trial of an educational intervention in high HIV prevalence practices in Bristol. The training delivered to HCPs including General Practitioners (GP) aimed to increase HIV testing and included why, who, and how to test. The intervention was adapted from the Medical Foundation for HIV and Sexual Health HIV Testing in Practice (MEDFASH) educational tool. Questionnaires assessed HCP feedback and perceived impacts of the intervention. HIV testing rates were compared between control and intervention practices using 12 monthly laboratory totals.Results169 HCPs (from 19 practices) received the educational intervention. 127 (75%) questionnaires were completed. Delivery of the intervention was received positively and was perceived as valuable for increasing awareness, confidence and consideration of testing, with HCPs gaining more awareness of HIV testing guidelines. The main pre-training HIV testing barrier reported by GPs was the patient not considering themselves at risk, whilst for nurses it was a concern about embarrassing or offending the patient. Most HCPs reported the intervention addressed these barriers. The HIV testing rate increased more in the control than in the intervention practices: mean difference 2.6 (95% CI 0.5,4.7) compared with 1.9 (− 0.5,4.3) per 1000 patients, respectively. The number of HIV tests across all practices increased from 1154 in the first 6 months to 1299 in the second 6 months, an annual increase in testing rate of 2.0 (0.7,3.4) from 16.3 to 18.3 per 1000 patients.ConclusionThere was a small increase in HIV testing rates over the study period, but this could not be attributed to the educational intervention. More effective and sustainable programmes tailored to each practice context are needed to change testing culture and HCP behaviour. Repeated training, supported by additional measures, such as testing prompts, may be needed to influence primary care HIV testing.Electronic supplementary materialThe online version of this article (10.1186/s12875-018-0880-9) contains supplementary material, which is available to authorized users.