Objective. To investigate the association between parental bonding styles and anxiety, depression, suicidal ideation, and self-efficacy beliefs in undergraduate medical students. Methods. A cross-sectional, self-administered survey involving 315 Brazilian medical students was conducted online. The Parental Bonding Instrument (PBI), the Generalized Anxiety Disorder-7 (GAD-7) scale, the 9-item Patient Health Questionnaire (PHQ-9), the Suicidal Behaviors Questionnaire-Revised (SBQ-R), and the general self-efficacy (GSE) scale were used. The internal consistency of the instruments used in the study was analyzed using Cronbach’s alpha. Multiple logistic regression models were applied, and the odds ratios (OR) and respective 95% confidence intervals (CI) were calculated to determine the association between parental bonding styles and anxiety, depression, suicidal ideation, and general self-efficacy beliefs. Results. In the analysis adjusted for sociodemographic variables, maternal affectionless control was associated with a greater risk of anxiety (
OR
=
2.48
; 95% CI: 1.15-5.33), depression (
OR
=
7.54
; 95% CI: 3.20-17.78), suicidal ideation (
OR
=
3.62
; 95% CI: 1.58-8.27), and low self-efficacy (
OR
=
3.81
; 95% CI: 1.76-8.25), while maternal neglectful parenting was associated with depression (
OR
=
3.24
; 95% CI: 1.17-8.96) and paternal affectionate constraint with suicidal ideation (
OR
=
3.09
; 95% CI: 1.36-7.02). Conclusions. These findings showed dysfunctional parenting styles to be associated with mental illnesses and low self-efficacy in Brazilian undergraduate medical students. This should be taken into consideration when treating medical students with mental disorders.