Rationale Dopamine stabilizers have stimulatory actions under low dopamine tone and inhibitory actions under high dopamine tone without eliciting catalepsy. These compounds are dopamine D₂ receptor (D₂R) antagonists or weak partial agonists and may have pro-mnemonic and neuroprotective effects. The mechanism underlying their stimulatory and neuroprotective actions is unknown but could involve sigma-1R binding. Objectives The present study examined sigma-1R and D₂R occupancy by the dopamine stabilizer pridopidine (ACR16) at behaviorally relevant doses in living rats. Methods Rats were administered 3 or 15 mg/kg pridopidine, or saline, before injection of the radiotracer ¹¹C-SA4503 (sigma-1R) or ¹¹C-raclopride (D₂R). Some animals received 60 mg/kg pridopidine and were only scanned with ¹¹C-raclopride. Cerebral ¹¹C-SA4503 binding was quantified using metabolite-corrected plasma input data and distribution volume (V _T) calculated by Logan graphical analysis. ¹¹C-raclopride binding was quantified using striatum-to-cerebellum ratios and binding potentials calculated with a simplified reference tissue model. Results Cunningham-Lassen plots indicated sigma-1R occupancies of 57 ± 2 and 85 ± 2 % after pretreatment of animals with 3 and 15 mg/kg pridopidine. A significant (44–66 %) reduction of ¹¹C-raclopride binding was only observed at 60 mg/kg pridopidine. Conclusions At doses shown to elicit neurochemical and behavioral effects, pridopidine occupied a large fraction of sigma-1Rs and a negligible fraction of D₂Rs. Significant D₂R occupancy was only observed at a dose 20-fold higher than was required for sigma-1R occupancy. The characteristics of dopamine stabilizers may result from the combination of high sigma-1R and low D₂R affinity.