Group housing calves is becoming more popular. This type of housing addresses welfare concerns and increases labour efficiency. However, calves are frequently regrouped according to growth rate in order to reduce live weight variability within groups. This study evaluated the consequences of repeated regrouping and relocation on calf welfare. Thirty-two pair-housed male Holstein calves were evaluated. Half the pairs were regrouped (placed in a new pen with a new pen-mate every week for 14 weeks). The other pairs stayed in the same pen with the same pen-mate. Following the first regrouping, calves increased their interactions with their pen-mate and their general activity compared to the non-regrouped calves. By the ninth regrouping, this increase in interactions and activity was not observed. More activity was observed at the end of the day and less at night by regrouped calves after they were all relocated to new pens. Regrouped calves had higher cortisol responses to exogenous adrenocorticotropin (ACTH) than non-regrouped calves. There were no differences between regrouped and non-regrouped calves in basal cortisol levels, ACTH responses to corticotropin-releasing hormone, activities of catecholamine-synthesizing enzymes (tyrosine hydroxylase and phenylethanolamine N-methyl transferase) and the incidence of health problems and growth rates. There were fewer abomasal ulcers found in regrouped calves. Overall, repeated regrouping and relocation did not appear to stress the calves. The calves rarely fought, and seemed to habituate to repeated regrouping.