Which is more important, marketing for new prospects or customer retention?

Customer retention is more important for the company's promotion

It reminds me a recent answer by Lubna to a post by Salah about80-20 rule.
I must quote this here, as its very relevant.
"20% of your customers contribute80% of your business revenue.
" So, retention is more important I believe.
Moreover, client who leaves your business will hardly refer your business to their friends and families.
Having said, getting new clients is also a must for the sake of growth and beating your competition.

Customer retention should b the first priority , it is very important as the business based on our retained customers, bt do marketing for new aspects should be deal with care as our future business based on it .

Both are important and parallel but what you really should ask yourself which approach has the priority if you are a new business you should focus on new prospects (dah ! ) if you already have customers (and by customers I mean frequent customers) you should focus on retain the customer rather than focus on the quantity but on the other hand you should not ignore looking for new prospects taking in account whether you can handle more customers or not.
read this page about law of diminishing returns http://en.wikipedia.org/wiki/Diminishing_returns I hope this answers your question

customer retention is one of the promotional tools which is one of the marketing tools or marketing programs called (marketing mix) which is one of the marketing jobs.

So always marketing is the base and most important.Marketing is at the first, last and everywhere in between

manily both.but if bussines has a long presence than priroty to new prospect: means new business than after CR.if business is a new than carefull for customer retaintion,it can ruin loyal customer,repeat business and new customer.

so depend on situation  and target segment  for marketing .

Looking at business operations from a cost perspective, a companyspends much less to retain customers than to prospect for new.  Both are vital to the health of a business and a balance much be reached.