Immunodiagnostic Systems Holdings' first half revenues are 4% down on last year due to a fall in antibody licence income from a large customer which had been expected.
It said that unaudited group revenues for the six months to the end of September £18.7m, 4% lower than the corresponding period last year.
On a like for like basis - that is at constant exchange rate and constant scope - group revenues declined by 11% year on year.
A trading update at market close on Friday said: 'Nearly all of this decrease was due to the decrease in antibody licence income from a large customer which had been expected.
'Without this decrease the decline amounted to 1% on a LFL basis.'
At 8:28am: (LON:IDH) Immunodiagnostic Systems Holdings PLC share price was -7.5p at 322.5p