Roles and responsibilities of Business Analyst

Business Analyst is accountable for solution requirements, acceptance and benefit monitoring (where assumptions and restrictions must be consider requirements too) while project manager is acountable for project (work needed) requirements. Project requirements are defined and managed from solution requitements. With that on hand, you will understand that the business analyst work starts before the project exists, continue while the project runs, do not end when the project ends. My recommendation is taking a look to Business Analysis for Practitioners Guide because in my personal opinion is a good reference about the interaction of both roles and could help to answer your question.

All good responses. The theoretical and practical answer to the question would be quite different though. Since most of the responses give the theoretical view I'll give the practical view - In a vendor environment I found that the BA is rarely involved before project initiation . The BA will also be used to overlap with the PM, more than it should. The primary focus of the BA is on creating documentation during the project life cycle. (There are many reasons but a different discussion) As you can see WHAT the BA does and WHAT the BA SHOULD be doing can be very different.