Ex-Chairman Ken Lay was joined by former Chief Executive Officer Jeff Skilling and former chief accountant Rick Causey in seeking separate trials, the Houston Chonicle reported. Lay had earlier requested his own trial.
U.S. District Judge Sim Lake said he would probably rule on the motions by early October.
The defendants claimed that they could not get a fair trial if the jury has to hear the case against the other former executives charged in the investigation.
The government is expected to oppose the request because some of the charges are related and it would be less costly for taxpayers to try them at once.
Attorneys for Causey said he would also have trouble getting an unbiased jury if he is forced to face trial with the more familiar co-defendants in the Enron investigation.
All three men have pleaded innocent. Causey and Skilling each face 35 or more charges of conspiracy, fraud and insider trading. Lay faces fewer charges, and four of them are related to his personal banking, not Enron.