In Washington DC, hundreds of exiles holding Tibetan and US flags bowed their heads in Lafayette park facing the White House at 16:00 GMT on Monday - midnight in Tibet on March 10, the day 50 years ago that the Dalai Lama fled – before marching to the Chinese embassy.
Similar rallies were expected around the world on Tuesday, including in the northern Indian town of Dharamshala where the Dalai Lama and his government live in exile.
Also on Tuesday, the US congress was to vote on a non-binding resolution that would call on China to "cease its repression of the Tibetan people, and to lift immediately the harsh policies imposed on Tibetans".
The bill, authored by Rush Holt, a Democrat, also urges China to respond to initiatives of the Dalai Lama to find a lasting solution on Tibet.
China brands the Dalai Lama a "splittist" bent on separating Tibet from China, but the Tibetan spiritual leader says he only wants autonomy for Tibet within China, and greater freedom to practise the region's form of Buddhism.
The Dalai Lama sneaked out of Lhasa on March 10, 1959 after China cracked down on an uprising against its rule.
Tibet's government-in-exile says that more than 80,000 people died between March and October of 1959 alone and that at least 200 more were killed last year when Chinese security forces clamped down on protests marking the anniversary.
China denies that it used violence to stop anniversary commemorations last year, saying instead that rioters were responsible for nearly two dozen deaths.