* Grant Pattison to resign as CEO from June 1

* Pattison engineered Wal-Mart sale

* Founder Lamberti has resigned as chairman

(Adds details and background)

By David Dolan

JOHANNESBURG, April 11 (Reuters) - The chief executive of South Africa's Massmart MSMJ.J will step down this year, the company said on Friday, after overseeing seven years of steady growth and engineering the sale of a majority stake to U.S. retailer Wal-Mart Stores WMT.N .

Grant Pattison will be replaced by his deputy, Chief Operating Officer Guy Hayward, from June 1, the discount retailer said in a statement. He will remain on the board as a non-executive director until the end of December.

Pattison is best known for steering the sale of a 53 percent in Massmart to Wal-Mart, the world's largest retailer. The high-profile 2011 deal was seen as a major vote of confidence in the retail potential in Africa's most developed economy.

However, it also sparked months of wrangling with unions and South Africa's government over conditions, including the use of local suppliers.

"The group is in good shape and well positioned for growth and I can think of no better time to hand over the reins," Pattison said.

Massmart shares were down 1.55 percent at 135.7 rand per share by 0924 GMT, slightly underperforming the all-share index which fell 1 percent.

Massmart Deputy Chairman Chris Seabrooke said the company was "saddened" by Pattison's decision.

Hayward joined Massmart in 2000. Previously he worked at Goldman Sachs in London.

The company also said Massmart founder Mark Lamberti had stepped down as chairman and a director as of April 10. Lamberti was recently appointed chief executive of logistics firm Imperial Holdings IPLJ.J . ID:nL6N0LP47F

Lamberti will be replaced by mining and investment executive Kuseni Dlamini.

(Editing by Joe Brock)

((david.dolan@thomsonreuters.com)(+27 11 775 3150)(Reuters Messaging: david.dolan@thomsonreuters.com@reuters.net))

Keywords: MASSMART CEO/