ObjectivesHospitalists are expected to be competent in performing bedside procedures, which are associated with significant morbidity and mortality. A national decline in procedures performed by hospitalists has prompted questions about their procedural competency. Additionally, though simulation-based mastery learning (SBML) has been shown to be effective among trainees whether this approach has enduring benefits for independent practitioners who already have experience is unknown. We aimed to assess the baseline procedural skill of hospitalists already credentialed to perform procedures. We hypothesised that simulation-based training of hospitalists would result in durable skill gains after several months.DesignProspective cohort study with pretraining and post-training measurements.SettingSingle, large, urban academic medical centre in the USA.ParticipantsTwenty-two out of 38 eligible participants defined as hospitalists working on teaching services where they would supervise trainees performing procedures.InterventionsOne-on-one, 60 min SBML of lumbar puncture (LP) and abdominal paracentesis (AP).Primary and secondary outcome measuresOur primary outcome was the percentage of hospitalists obtaining minimum passing scores (MPS) on LP and AP checklists; our secondary outcomes were average checklist scores and self-reported confidence.ResultsAt baseline, only 16% hospitalists met or exceeded the MPS for LP and 32% for AP. Immediately after SBML, 100% of hospitalists reached this threshold. Reassessment an average of 7 months later revealed that only 40% of hospitalists achieved the MPS. Confidence increased initially after training but declined over time.ConclusionsHospitalists may be performing invasive bedside procedures without demonstration of adequate skill. A single evidence-based training intervention was insufficient to sustain skills for the majority of hospitalists over a short period of time. More stringent practices for certifying hospitalists who perform risky procedures are warranted, as well as mechanisms to support skill maintenance, such as periodic simulation-based training and assessment.