Five-week-old male Wistar rats were used to study the effect of dietary therapy with ipriflavone combined with 1&alpha;-OH-D₃. Ultrastructural alterations in the metaphysis of debilitated tibia were observed in the growing rats.<br>I. Light microscopy findings<br>In the low-calcium diet&middot;standard diet with supplementary ipriflavone and 1&alpha;-OH-D₃ group, calcification of the chondral matrix and ossification were active, and the tibia grew normally as in the control group.<br>II. Scanning electron microscopy findings<br>In the low-calcium diet&middot;standard diet with supplementary ipriflavone and 1&alpha;-OH-D₃ group, dense calcospherites, distinct chondral lacunae, regularly running collagen fibers, and distinct border lines were noted.<br>III. Transmission electron microscopy findings<br>In the low-calcium diet&middot;standard diet with supplementary ipriflavone and 1&alpha;-OH-D₃ group we found that the osteoblasts were active, the ruffled border of osteoclast was decrease, indicated this osteoclast is inactive.<br>In conclusion, insufficient calcium intake during the developmental period resulted in debilitated(3etaphysis tibia, whereas dietary therapy using combined ipriflavone and 1&alpha;-OH-D₃ promoted recovery.