Benzo[a]pyrene (B[a]P) is a ubiquitous environmental pollutant exhibiting adverse effects on cognitive function and behaviour. In this study, depressive or antidepressive effects of B[a]P were investigated. Here, we report that a subacute B[a]P oral exposure (0.020.2 mg/kg) increases mobility behaviour in female adult mice in the tail suspension test, but not in the forced swimming test, without altering locomotion, suggesting that the tail suspension test was a more sensitive indicator of B[a]P-induced neurobehavioural disturbance. This might be because of differences in neurochemical substrates and pathways, mediating the performance in these behavioural models of depression. The effect of B[a]P on female adult mice in the tail suspension test was similar to that obtained with subacute treatment of the antidepressant reference drug imipramine (10 mg/kg). Therefore, B[a]P at 0.02 mg/kg and 0.2 mg/kg induces an antidepressant-like effect in mice, suggesting a neurobehavioural disturbance after oral exposure to this environmental compound. Furthermore, oral exposure to B[a]P at 0.02 mg/kg significantly increased gene expression levels of the brain receptors 5-hydroxytryptamine (serotonin) 1A (5HT1A) and alpha-1D adrenergic (ADRA1D). In summary, the presented findings suggest that subacute oral exposure to B[a]P results in behavioural changes in female adult mice, possibly caused by alterations in the serotoninergic and adrenergic systems.