UPDATE 1-Galapagos H1 misses forecasts, keeps guidance

* Net loss shrinks to 7.3 mln euros vs mkt forecast of 7 mln

* Revenue rises to 37.7 mln euros vs mkt forecast of 40 mln

* Keeps 2009 guidance for 100 mln euros in revenue

* Keeps guidance for 20 mln euros in year-end cash

* Shares rise 3.9 pct at open

(Recasts, adds detail, CEO comment, share price)

BRUSSELS, Aug 7 (Reuters) - A delayed milestone payment pushed Belgian biotechnology group Galapagos NV's (GLPG.BR) (GLPG.AS) first-half earnings just below market expectations, with a slightly wider loss and thinner revenue than foreseen.

Galapagos on Friday repeated its earlier guidance for 100 million euros ($143.8 million) in full-year revenue and 20 million euros in year-end cash, saying it was on track with clinical trials and was managing to keep costs down.

Chief Executive Onno van de Stolpe told a conference call the somewhat weaker-than-expected top and bottom lines were due to a delay in a milestone payment from one of Galapagos's alliances.

He declined to say which, only that the payment would arrive.

"These milestones are quite chunky. A milestone that is delayed by a couple of months has an impact on total revenues. But we anticipate milestones to come in according to plan over the whole year, so we're able to confirm the guidance," he said.

The bone and joint specialist said it had burned through 8.6 million euros in cash in the first six months of 2009, versus 21.9 million in the same period last year.

The reduced spending was largely thanks to an improved performance by BioFocus DPI, Galapagos's service unit.

In addition, much of Galapagos's revenue stems from alliances with blue-chip players such as Merck & Co Inc (MRK.N), Eli Lilly and Co (LLY.N), GlaxoSmithKline Plc (GSK.L) and Johnson & Johnson's JJ.N Janssen Pharmaceutica.

Galapagos reported a net loss of 7.3 million euros against a market forecast of 7 million, according to the average estimate from a Reuters poll of three analysts.

Revenue of 37.7 million euros fell short of the 40 million average analyst forecast.

Galapagos shares traded up 3.9 percent to 8.1 euros as of 0715 GMT, against a 0.5 percent drop for the DJ Stoxx European Healthcare index .SXDP. (Reporting by Anne Jolis; Editing by John Stonestreet and David Holmes) ($1=.6954 Euro)