The objective of the study was to investigate the effect of only concentrate diet on growth and rumen development of Holstein calves during preweaning period. Thirty female and nine male calves were allocated to three treatments. Nine male calves were also divided into three treatments to operate for rumen wall samples. First group was fed with a calf starter and alfalfa hay as free choice, second group was received calf starter only and third group were fed with a total mixed ration (TMR) during the pre-weaning period. The average daily gain of the free choice, calf starter only and total mixed ration groups were 528.39 +/- 29.82, 509.00 +/- 34.08 and 479.21 +/- 25.86 g respectively. The average daily feed intake of the groups were 672.75 +/- 69.86, 619.73 +/- 77.75 and 499.60 +/- 81.69 g respectively. Calf starter group showed similar performances to free choice and TMR group of calves (P > 0.05). Protozoa number were not significantly different among the treatments while total bacteria numbers were higher for calf starter group than the other two groups (P < 0.05). The calves received calf starter only had flatter and more branched papillae than did the other calves. These results revealed that it is possible to rear calf successfully without roughage during preweaning period.