* China manufacturing struggles in March but shows expansion
* ISM, Markit manufacturing on tap
* Medicines Co tumbles after court ruling
* Futures up: Dow 41 pts, S&P 4.5 pts, Nasdaq 8.75 pts
By Chuck Mikolajczak
NEW YORK, April 1 (Reuters) - U.S. stock index futures rose modestly on Tuesday, indicating the S&P 500 will climb for a third straight day, after the benchmark index closed its fifth straight quarter of gains and ahead of data on manufacturing.
* The S&P 500 rose 1.3 percent for the quarter, matching its longest quarterly winning streak since 2007, buoyed by gains Monday after Federal Reserve Chair Janet Yellen soothed concerns about an earlier-than-expected rate hike.
* Investors will look to data on the manufacturing sector for an indication of the economy's health after lackluster data earlier in the year was attributed to a harsh winter. The final Markit manufacturing PMI for March is due at 9:45 a.m. EDT (1345 GMT) and the Institute for Supply Management's manufacturing reading for March is due at 10:00 a.m. (1400 GMT).
* ISM is expected to show a reading of 54 versus the prior 53.2. The prior Markit reading came in at 55.5.
* S&P 500 e-mini futures rose 4.5 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures gained 41 points and Nasdaq 100 futures added 8.75 points.
* Construction spending data for February is also due at 10:00 a.m. (1400 GMT). Expectations call for a flat reading versus the prior gain of 0.1 percent.
* Two surveys showed manufacturing in China struggled in March but managed to show expansion, with activity at smaller, private firms contracting for a third month, adding to a run of disappointing data that has sparked speculation of imminent government-led stimulus.
* Medicines Co tumbled 13.2 percent to $24.68 in premarket trade. The company said a federal judge in Delaware upheld two patents related to Hospira Inc's generic version of Medicines Co's angiomax product.
* European stocks got off to a brisk start in the second quarter, with merger-and-acquisition activity driving gains by industrial and mining stocks.
* Asian shares hit a four-month high after dovish comments from Federal Reserve Chair Janet Yellen and China's manufacturing data. (Editing by Bernadette Baum)