How to make div height 100% ?

Hi,
Actually i am designing one table in div via css. Now problem is one col of div having more data then other, due to this reason this cell or div expended, having fixed width which i have declared but height increased according to its data. I want if one cell height increased then corresponding cell in same row, height will also rise but thats not happen, which is my problem. I also make height 100% but its not working.
So, if any one have solution, please suggest me to resolve this issue. If any thing more you want please let me know.
Thanks in Advance.