Sales of around $42bn are expected, according to consensus estimates from analysts polled by Reuters and earnings per share of $1.38.
That's down from last year's $49.6bn and $1.85 earnings per share but in line with Apple's own $41bn - $43bn guidance.
Last quarter, revenue of $50.6bn missed estimates by around $2bn.
Sales of iPhones this time last year were 61.2m, but, this year analysts expect a more muted 40m - 43m. That would also be a decline on the 51.2m sold last quarter.
iPhones accounted for 65 per cent of revenue in the previous quarter.
Apple stock has fallen five per cent in the last three months and around six per cent since the start of the year. Shares are more than 26 per cent down on last year's all-time high in April last year.
Why it's interesting
Apple is guided by its iPhone production cycle and with the next major model upgrade due in Autumn, that lull is being fully felt despite the holdover of the iPhone SE earlier this year.
That phone, it should be noted, is also a lower end (ie. cheaper) version than its usual flagship models, so good sales figures for that device won't bring in the equivalent revenue with the same numbers as, say, the iPhone 6s.
All eyes will be on the growing Apple services such as Apple Pay and Apple Music and whether these numbers will go some way to mapping out sources of ongoing revenue (and dedication to Apple products) outside of the upgrade cycle.
Of course, Apple remains the biggest company in the world and has large cash reserves; analysts expect a recovery in iPhone sales with the iPhone 7.
This will probably be an earnings that Apple would rather forget, but it's one to watch to get a sense of the tech company aside from those all-important iPhone numbers.