In attendance with me today are Steve Sanghi, Microchip's President and CEO; Ganesh Moorthy, Microchip's COO; and Gordon Parnell, Vice President of Business Development and Investor Relations. I will comment on our first quarter of fiscal year 2013 financial performance, and Steve and Ganesh will then give their comments on the results, discuss the current business environments and discuss our guidance. We will then provide an update on our acquisition of SMSC and be available to respond to specific investor and analyst questions.
Before I jump into the details, I want to remind you that we are including information in our press release and this conference call on various GAAP and non-GAAP measures. We have posted the full GAAP to non-GAAP reconciliation on the Investor Relations page of our website at www.microchip.com, which we believe you will find useful when comparing GAAP to non-GAAP results.
I will now go through some of the operating results, including net sales, gross margin and operating expenses. I will be referring to these results on a non-GAAP basis, prior to the effects of our acquisition activities and share-based compensations. Non-GAAP net sales in the June quarter were $352.4 million and were up 4% from net sales of $338.9 million in the immediately preceding quarter. Non-GAAP net sales were about $250,000 higher than GAAP net sales as GAAP does not recognize revenue on the sell-through of products sitting in the distribution channel on the date of an acquisition. This $250K difference relates to our April acquisition of Roving Networks. We expect we will have larger differences in the coming quarters in our GAAP and non-GAAP net sales due to the acquisition of SMSC.
On a non-GAAP basis, gross margins were 59% in the June quarter and non-GAAP operating expenses were 26.3% of sales. Operating income was 32.7% of sales and net income was $96.9 million. This resulted in earnings of $0.48 per diluted share, which was at the midpoint of our guidance.