Tyco runs a wide range of businesses
The news lifted Tyco's battered share price 3% to $28.3.
But this is still a far cry from the heights of $60 seen last December.
The allegations - brought in 38 separate so-called class-action law suits - centered on Tyco's disclosures and accounting practices.
Since the collapse of Enron, investors have grown increasingly nervous of companies whose accounts they find opaque or confusing.
Enron's apparent success began to unravel last October and gradually revealed a mass of accounting scams that hid the massive losses from shareholders and analysts.
Falling short of fraud
Tyco owns a complex network of companies in sectors ranging from fire alarm systems to undersea cables and medical equipment.
It has made more than 200 acquisitions in the past three years, and its books have been complicated by tax-avoidance schemes.
The company said in a statement that the US District Court found the plaintiffs "had fallen well short of stating a viable securities fraud claim."
The lawsuit had consolidated 38 class-action suits filed in various federal courts dating back to December 1999.
"The dismissal of these lawsuits should help allay concerns that have been raised about Tyco's accounting practices," said the firm's chief executive Dennis Kozlowski.
"We remain focused on the key task of unlocking shareholder value," he added.