This was a big drop from the US$49.6 billion in the third quarter of the previous financial year. That quarter saw profit of US$10.7 billion, which means a fall this time of nearly 25%.
This is the second consecutive quarter in which Apple's sales have shown a downward trend.
iPhone sales were down to 40.4 million units, compared to 48 million for the third quarter of the previous financial year. Overall sales in China fell by a third from the previous year.
However the iPhone sales figures for the quarter exceeded analysts' expectations which were 40.02 billion.
The company's services business, which includes the App Store, Apple Pay, iCloud and others, generated nearly US$6 billion in revenue, a rise of 18.9% compared to the corresponding quarter in the previous financial year.
Apple chief executive Tim Cook said, "We are pleased to report third-quarter results that reflect stronger customer demand and business performance than we anticipated at the start of the quarter. We had a very successful launch of iPhone SE and we're thrilled by customers' and developers' response to software and services we previewed at WWDC in June."
Apple chief financial officer Luca Maestri said: "Our Services business grew 19% year-over-year and App Store revenue was the highest ever, as our installed base continued to grow and transacting customers hit an all-time record.
"We returned over US$13 billion to investors through share repurchases and dividends, and we have now completed almost US$177 billion of our US$250 billion capital return programme."