[en] PSMA-PET has become the PET technique of choice to localise the site of biochemically recurrent prostate cancer (PCa). With hybrid PET/MRI, the advantages of MRI are added to molecular characteristic of PET. The aim of this study was to investigate the incremental value of PET/MR versus PET/CT in patients with biochemically recurrent PCa by head-to-head comparison. Thirty-four patients with biochemically recurrent PCa were prospectively included. They underwent [${}^{68}$GA]Ga-PSMA-11 PET/CT, followed by simultaneous PET/MR. All PET (PET${}_{CT}$, PET${}_{MR}$), CT and MR images were evaluated for number of lesions and location. The number of lesions at specific sites was compared using Wilcoxon-sign-rank test. For PET, the maximum and mean standardised uptake values (SUVs) were calculated for each lesion compared using a two-sided paired t test. PET${}_{CT}$ and PET${}_{MR}$ scans were positive in 19 and 20 patients, detecting 73 and 79 lesions respectively. All lesions detected on PET${}_{CT}$ were also detected on PET${}_{MR}$. CT and MRI only were positive in 14 and 17 patients, detecting 38 and 50 lesions, respectively, which was significantly lower than PET${}_{CT}$ and PET${}_{MR}$ respectively. Combined interpretation showed more lesions on PET/MR than on PET/CT (88 vs 81). No significant difference in detection of presence of local recurrence nor distant metastases was found. SUV${}_{mean}$ and SUV${}_{max}$ values were significantly higher on PET${}_{MR}$ than on PET${}_{CT}$ in local recurrence and lymph node metastases. [${}^{68}$GA]Ga-PSMA-11 PET/MR was able to detect biochemically recurrent PCa at least as accurately as PET/CT for local recurrence, lymph node metastasis and distant metastasis. PSMA PET/MRI detects the location of biochemical recurrence at least as accurately as PET/CT. Substitution of PET/CT by PET/MRI adds sensitivity in PSMA lesion detection also in the setting of distant recurrence due to both the MR and TOF PET components.