A wheelchair-bound man has been threatened, yanked from his chair and robbed in Sydney's west.

The 40-year-old was on Macarthur Street at Rosehill about 9.45am (AEDT) on Saturday when he was approached by two men.

The pair threatened the man, pulled him out of his chair and stole his leather bag, containing cash and a mobile phone, before running away, police said on Sunday.

The 40-year-old managed to get back on his wheelchair before attending a nearby medical centre.

The first man is described as being thin, in his mid-30s, of black African appearance and about 170cm tall.

The second man is described as being solid, in his mid 30s, of Caucasian appearance, with blond hair and about 180cm tall.

Anyone with information should call Crime Stoppers on 1800 333 000.