The Sri Ramachandra hospital in the southern city of Chennai said that the 61-year-old Tamil language cinema icon was moved to a special ward on Wednesday to improve his breathing.
"He is showing a positive response to the treatment," the hospital said in a statement issued Wednesday evening.
Rajinikanth, a former bus conductor turned actor, fell ill on the first day's shooting of his new film "Rana" (The Monarch) at the end of April and has been admitted twice to hospital.
He has been in the private Sri Ramachandra hospital since last Friday. Medical sources said he is being treated for pneumonia and a kidney ailment.
On Monday, doctors removed fluid from his chest that was causing breathing difficulties.
"A multi-disciplinary team is closely watching his vital parameters to assess the benefits from a multi-pronged treatment strategy," the hospital statement said.
Rajinikanth, who has starred in more than 175 films, is one of India's biggest movie stars and inspires fanatical devotion from his many fans.
One fan, Karthik H, wrote on the micro-blogging site Twitter, "You have problematic kidneys? I have two clean ones. Take one. Please get back to acting soon."
The star's family, though, has urged fans not to hold a vigil at the hospital but instead to offer prayers at local temples.
Last year he starred in "Endhiran" (Robot), the most expensive Indian movie ever made, which broke box office records. (AFP)
