Two 6‐week feeding trials were conducted on a total of 112 newly weaned piglets to examine the recently reported growth promoting effects of dietary rare earth elements (REE) in European pig production. Rare earth element‐diets were supplemented with a REE‐citrate premix of lanthanum and the light lanthanoides cerium, praseodymium and neodymium at 200 mg/kg for 6 weeks after weaning. Overall for both trials, growth performance of REE‐citrate and control fed piglets did not differ significantly (p > 0.05). An early enhancive tendency for REE‐citrate in trial 1 (feed conversion ratio, FCR −3%, p = 0.15) proved irreproducible in trial 2. In the late period of trial 1, in‐feed addition of REE‐citrate significantly impaired piglet performance (FCR + 8%, p =0.01). A cultivation‐independent molecular approach, polymerase chain reaction‐denaturing gradient gel electrophoresis was further applied to assess REE induced alterations in the predominant faecal microbiota from weaning pigs. Calculation of various ecological characteristics does not indicate (p > 0.05) an often discussed selective effect on local microbial composition of dietary REE.