Serious illness is no joking matter. But experts say an upbeat attitude might help.

At Montefiore Hospital in the Bronx, cancer patients — some with advanced stages of the illness — are getting a boost through a therapy program called "Strength Through Laughter."

It's among several types of humor therapy being offered by medical facilities around the country for patients diagnosed with cancer or other chronic diseases.

The programs range from joke sessions to clown appearances to viewing of humorous movies.

The verdict is still out on whether laughter plays a role in healing. But the American Cancer Society and other experts say it reduces stress and promotes relaxation by lowering blood pressure, improves breathing and increases muscle function.