Mr McNamee will be replaced by Paul Perreault, president of the CSL Behring division, which accounts for 85 per cent of company revenue.

Shares in the blood plasma and vaccine maker were recently down 80 cents, or 1.9 per cent,  to $40.55.

Its shares have risen by 27.5 per cent this year, a surge Wilson HTM healthcare analyst Shane Storey says has been driven by "latecomer interest" and CSL "embarrassing the competition" in the American market.

Dr Storey said that although it was not a surprise to see Mr McNamee go, due to the company flagging his departure several years ago, it was sad news.

"Im sure the new guy is a very capable person, but there was something about Brian."

He added that Mr McNamee might have timed his exit beautifully, describing CSL as "way overvalued".

Commonwealth Bank analyst Bruce Du said the appointment of Mr Perreault made sense, given CSL's preference for promotion from within, and the Behring business being "by far the largest and most important segment."

"It's a natural transition," he said.

UBS healthcare analysts Andrew Goodsall and Dan Hurren said that Mr Perreault was "well regarded by the market and industry" and they expected no earnings impact from the change.

"On UBS observation, Brian's great strength was the 'strategic' and Paul's great  strength is the 'commercial'," the pair said in a note.

"Perreault will run a dual US/Australia head office; again defining the global transition of the company. McNamee will not stay on the board, allowing new  CEO opportunity to act with own 'freedom'; this seems rational to us.

"Understandably, the market will reminisce the legacy of an outstanding Australian CEO who was rated as bringing globally talented leadership to CSL over past 23 years.

"UBS assessment is [the] CSL 5-year strategic direction and earnings, both plasma and recombinant products (via R&D  portfolio) is well defined and execution is largely down to commercialisation now."

Mr McNamee will stay with the company until June 2013.

Meanwhile, an application by CSL to the industrial umpire to stop industrial action at its Broadmeadows plant has been scheduled for this weekend.

CSL went to Fair Work Australia this week seeking the termination of a ban of processing of international plasma by three unions.