It could indicate too much/little water, inadequate light, need for fertilization, or a need for repotting. In any case, "pruning" will not help. Bamboo are not like other plants in this regard. All pruning will do is permanently remove branches that will never grow back, and it will not stimulate growth. I can't tell you exactly what is wrong given the little info provided, but I can tell you that pruning is not the solution.

I agree with Kudzu, pruning will NOT solve the problem.

However, the yellowing leaves could also be seasonal or the seasonal changing of the leaves, but it may be happening in conjuction with any combination of the problems that Kudzu mentioned also.

Kt

Thank you both for your quick replies. Okay, NO PRUNING..got it! Hmmm, okay most likely seasonal changes then. I fertilized it last week with a little bit of lawn fertilizer. I haven't watered it because it is already moist. It is sitting in a sunny spot and it has several new shoots. Should it be kept in the sun? Thanks again for your help.

cadence-
That all sounds fine. Sun is good as long as the soil is moist. I'm wondering how big the plant is in relation to the pot. Can you post a picture of what you are dealing with?