Two experiments were conducted to evaluate the involvement of dietary protein and short-term chilling on the incidence of diarrhea and on transit time of digesta in pigs weaned at 3–4 wk of age. The three protein sources used were buttermilk powder (BMP), soybean meal (SBM) or pea protein concentrate (PPC), which provided 85% of the dietary protein. In exp. 1, 72 pigs were exposed to a 16 °C decrease in ambient temperature for 8 h on day 4 of a 9-day feeding trial; 72 pigs were not chilled. The pigs on the PPC diet gained less (539 g) (P < 0.05) than pigs on BMP (1183 g) or SBM (952 g) although intakes were similar. Neither diet nor chilling affected fecal moisture content or the incidence of diarrhea. The PPC ration increased (P < 0.05) transit time (slowed rate of passage) on day 8. Chilling on day 4 decreased (P < 0.05) transit time (18.7 vs. 25.6 h) on that day. Neither protein source nor chilling caused differences in total or coliform bacteria isolated from fecal samples on blood agar or MacConkey's agar. In exp. 2, eight chilled and nine control pigs were euthanized and the quantity of three markers in six segments of the gastrointestinal tract was determined. The PPC diet passed more slowly than the other diets. In chilled pigs, the chromic oxide front was closer to the anus, indicating an increased rate of passage. It was concluded that the severity of the cold exposure was not suffficient to induce diarrhea and that there was no interaction between the effects of chilling and of dietary protein. There was, however, a tendency for chilling to increase the rate of passage of digesta which could have an additive effect on the severity of nutritional diarrhea. Key words: Pigs, weaning, diarrhea, protein, cold, transit time.