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tokens: al. ( 2014 ) also suspected the existence of tidal tails for NGC 3201, as they found some unbound stars located a few arc minutes outside of the cluster radius. Recently, Anguiano et al. ( 2016 ) reported the presence of tidal debris for the cluster. Their results were based on spectroscopic measurements from RAVE data. NGC 5024 has five extra-tidal RR Lyrae stars mostly concentrated in a region which is at a distance of three times the tidal radius from the centre of the cluster. The presence of these extra-tidal RR Lyrae stars may be an indication of more extra-tidal population which may also belong to the cluster. Beccari et al. ( 2008 ) found that in the case of NGC 5024, the model with lower concentration ( c = 1.45) and large core radius ( r c = 26 arcsec) best reproduced the observed surface density profile in the inner portion of the cluster but this model deviates from observations in the outer region of the cluster. This type of deviation is a signature of the stars that are tidally stripping away from the cluster (Combes et al. 1999 ; Johnston, Sigurdsson Hernquist 1999 ; Leon et al. 2000 ). Kunder et al. ( 2018 ) reported eight extra-tidal RR Lyrae stars belonging to the Galactic globular cluster NGC 6441 but we did not find any in this study. This is due to three reasons: (1) some of the stars reported by them were not observed in Gaia DR2 (OGLE BLG-RRLYR-3774, OGLE BLG-RRLYR-30603, OGLE BLG-RRLYR-30792, OGLE BLG-RRLYR-3168, OGLE BLG-RRLYR-31080); (2) star reported was not marked as variable by Gaia survey [OGLE BLG-RRLYR-30513 ( Gaia DR2 4039957151898674048)] and (3) stars were reported as RRab variable stars by Gaia survey but were not present in Gaia DR2 RR Lyrae catalogue [catalogue: gaiadr2.vari_rrlyrae; stars: OGLE BLG-RRLYR-3613 ( Gaia DR2 4039958564974057984)], [OGLE BLG-RRLYR-30928 ( Gaia DR2 4039978695412672768)]. Minniti et al. ( 2018 ) recently reported the presence of tidal tails in the cluster NGC 6266. These were not found in our analysis due to the fact that they used additional near-IR VVVX survey observations along with Gaia DR2 data. 5 CONCLUSIONS We searched for extra-tidal RR Lyrae stars in 56 Galactic globular clusters based on the available literature data. Gaia DR2 data for RR Lyrae stars from the catalogue of Clementini et al. ( 2018 ) were used along with data from MPV14 and V18 to assign cluster membership to each RR Lyrae star. The extra-tidal RR Lyrae stars were selected based on three criteria: position of the cluster and the star in the sky; proper motion of the cluster and the star; and position of the RR Lyrae star on the CMD of the cluster. All the three criteria are necessary and none of them can be neglected while selecting the extra-tidal RR Lyrae stars. Based on these three criteria we found 30 extra-tidal RR Lyrae stars belonging to 11 globular clusters. The majority of these clusters have only a couple of candidates. We also note that some of those extra stars for halo GCs may also be part