Two trials were conducted to determine if pigs should be sorted by weight at the beginning of the growing/finishing phase and if this decision is dependent upon the use of all in/all out (AI/AO) or continuous pig flow management. Pigs were classified by their relative weight as Heavy, Medium or Light prior to allocation to pens. Within each gender, pigs were allocated to create uniform pens, consisting entirely of Heavy, Medium and Light pigs, respectively, and variable pens consisting of two or more of the weight classes. In addition to standard growth and intake data, behaviour data on aggression and time budgets were collected on the pigs. There were no deleterious effects of having variable weight pens. Average daily gain (ADG), and behaviour did not differ between pigs in uniform and variable weight pens. The rate of pen and room emptying differed depending upon the pig flow management system and grouping strategy. Under a continuous flow system, pens were emptied in an average of 105.5 days, while under an AI/AO system the rooms were emptied in an average of 107.5 days. Uniform and variable weight pens emptied at the same rate under the continuous flow system. Under the AI/AO system, rooms of variable weight pens emptied faster (104.1 days) than did rooms of uniform weight pens (110.9). Sorting pigs by weight into uniform pens at the beginning of the growing/finishing phase is not advantageous, and may be detrimental to rapid turn-over of rooms under an AI/AO management system.