Former Taiwan president Chen Shui-bian was cheered by marchers
Tens of thousands of pro-independence Taiwanese have demonstrated against China, accusing President Ma Ying-jeou of failing to stand up to Beijing.
The opposition marchers in Taipei highlighted a recent scare over dairy products in China, and accused Taiwan's government of playing down the issue.
Relations between China and Taiwan have improved dramatically since Mr Ma came to power in May promising closer ties.
China still regards Taiwan as part of its territory.
The previous Taiwanese government, led by the Democratic Progressive Party (DDP), had antagonised Beijing with its pro-independence agenda.
Visit from the mainland
During Saturday's march, organised by the DPP, protesters shouted such slogans as: "Opposing toxic products, defending sovereignty."
At least three babies have died in China's tainted milk powder scandal and many more have been taken ill.
Former Taiwan President Chen Shui-bian, also of the DPP, joined the marchers and was cheered by the crowd.
The demonstration comes nine days before a planned visit by Chen Yunlin, Beijing's top negotiator on Taiwanese affairs.
The two sides are expected to discuss new direct flights and food safety.