The increased loss caused shares in the San Diego SNP-genotyping company to fall 14.68 percent, or $1.91, to $11.10 during mid-afternoon trading.
Revenues totaled $15.8 million for the quarter, a 38-percent increase over last year's $11.5 million for the same period.
The company's research and development expenses climbed to $7.3 million, up from $5.3 million during the year-ago period.
Illumina's net loss amounted to $18.5 million, or $.46 per share, up from $3.5 million, or $.10 per share, during last year's second quarter. This included a $15.8 million write-off of in-process research and development that Illlumina acquired with CyVera in April.
As of July 3, Illumina had $54.6 million in cash and investments.