The technology giant reported quarterly sales of $50.56bn (£34.39bn) down from $58bn last year - the first fall in sales for the company since 2003.
Apple sold 51.2 million iPhones during the quarter, down from 61.2 million in the same quarter of 2015.
China was a particular weak spot - sales there fell 26%. Results were also hit by the impact of a stronger dollar.
Apple shares fell 8% in after hours trading. Its shares have fallen close to 20% over the last twelve months.
Apple's chief executive Tim Cook said the company performed well "in the face of strong macroeconomic headwinds".
Apple's quarterly profit slipped to $10.5bn from $13.5bn.
Nevertheless, it announced it would return $50bn to shareholders through an increase in share buybacks and a 10% increase in quarterly dividends.
(BBC News)