Background: Personality disorder (PD) is associated with elevated suicide risk, but the level of risk in primary care settings is unknown. We assessed whether PD among primary care patients is linked with a greater elevation in risk as compared with other psychiatric diagnoses, and whether the association is modified by gender, age, type of PD, and comorbid alcohol misuse. Methods: Using data from the UK Clinical Practice Research Datalink, 2384 suicides were matched to 46,899 living controls by gender, age, and registered practice. Prevalence of PD, other mental disorders, and alcohol misuse was calculated for cases and controls separately and conditional logistic regression models were used to estimate exposure odds ratios. We also fitted gender interaction terms and formally tested their significance, and estimated gender age-specific effects. Results: We found a 20-fold increase in suicide risk for patients with PD versus no recorded psychiatric disorder, and a four-fold increase versus all other psychiatric illnesses combined. Borderline PD and PD with comorbid alcohol misuse were associated with a 37- and 45-fold increased risk, respectively, compared with those with no psychiatric disorders. Relative risks were higher for female than for male patients with PD. Significant risks associated with PD diagnosis were identified across all age ranges, although the greatest elevations were in the younger age ranges, 16-39 years. Conclusions: The large elevation in suicide risk among patients diagnosed with PD and comorbid alcohol misuse is a particular concern. GPs have a potentially key role to play in intervening with patients diagnosed with PD, particularly in the presence of comorbid alcohol misuse, which may help reduce suicide risk. This would mean working with specialist care, agreed clinical pathways and availability of services for comorbidities such as alcohol misuse, as well as opportunities for GPs to develop specific clinical skills.