This study aimed to determine the effects of housing conditions and glutamine (GLN) levels on growth performance and incidence of diarrhea in weaned piglets. Forty-eight piglets were randomly assigned (4x2 factorial design) to one of the eight experimental diets represented by four levels of dietary GLN (0.0, 1.0, 1.5 or 2.0 %) and two housing conditions (AD = adequate and INAD = inadequate). From 22 to 28 days of age all animals were challenged daily with Escherichia coli polysaccharides. No effect of GLN level was found on daily gain (ADG), daily feed intake (ADFI) or body weight at 28 days postweaning (BW28). For housing conditions, ADG at 21 days after weaning was greater for animals of treatment AD than INAD, and AD had lower body weight variation than INAD pigs at 21 days after weaning. Considering the whole period, AD had a higher ADG, ADFI and BW28 than INAD. However, an interaction effect was observed for feed:gain rate, in which values decreased linearly (Y = 2.1727 -0.4017x; R 2 =0.92) just for AD pigs as GLN levels increased. No GLN level effects were observed for diarrhea incidence; however, AD had a higher number of animals without diarrhea and with lower incidence of severe diarrhea than INAD pigs. In conclusion, supplementing GLN doesn't affect ADG, ADFI or BW28 but it improves feed efficiency when housing conditions are adequate. Key words: Amino acid. Housing condition. Lps. Pigs. Weanling. ResumoEste estudo visou determinar o efeito das condições de alojamento e dos níveis de glutamina (GLN) sobre o desempenho e a incidência de diarréia em leitões desmamados. Quarenta e oito leitões foram divididos aleatoriamente (modelo fatorial 4x2) e submetidos a oito dietas experimentais representadas por quatro níveis de GLN dietética (0.0, 1.0, 1.5 ou 2.0 %) e duas condições de alojamento (AD = adequada e INAD = inadequada). A partir do 22º dia de idade até os 28 dias de experimentação, todos os leitões foram desafiados com lipopolissacarídeo de Escherichia coli. Nenhum efeito do nível de