Netflix Inc., United States’ largest online DVD rental service, said it recorded its sixth quarter with profit growth in a row on the growing number of customers and the decreasing cost of adding.

Netfix shares climbed 7.8 percent.

The Los Gatos, Calofornia- based company posted a net income growth for the second quarter of fiscal year 2008 of 3.8 percent to $26.6 million, or 42 cents a share. During that same period last year, Netflix earned $25.6 million, or 37 cents, the company said today in a statement.

The profit growth was within the company’s forecast of 33 cents to 42 cents and surpassed the estimations made by analysts surveyed by Bloomberg who were expecting a growth of 40 cents (on average).

Netflix, which has more than 55 million discs and ships 1.9 million of them to customers each day (on average), saw its sales increase 11 percent to $337.6 million. The company’s leadership forecasted a second-quarter revenue of $334 million to $339 million.

Netflix reduced its prices last year in order to draw more customers. The strategy contributed to the firm’s lowest cost to bring on new subscribers since Netflix became a public company in May 2002 according to its CEO Reed Hastings. Subscriber-acquisition costs dropped 34% to $28.95, while the rate of customer cancellations fell to 4.2% from 4.6%.

In May, the company introduced a new device which allows movies sent by mail to be watched on television, a move which Hastings hopes will help the company grow to 20 million users.

Netflix, which sends movies by mail, finished the quarter with 8.4 million subscribers, while net subscriptions rose 168,000. As for the company’s near future, Netflix leaders forecast a third-quarter net income of 26 cents to 34 cents a share on revenue of $343 million to $348 million.

For the entire fiscal year 2008, the company boosted its per-share forecast to some extent, to a range of $1.19 to $1.31. The revenue view was tightened to $1.36 billion to $1.38 billion.