* Q4 $4.47 ex-items vs $4.45 consensus: Reuters Estimates

* Some analysts see small miss, in-line with forecasts

* Sales rise 1 pct to $2.23 bln

* Shares fall 5.1 percent

AutoZone Inc (AZO.N), the largest U.S. auto-parts retail chain, posted quarterly results on Wednesday roughly in-line with analysts' expectations as same-store sales growth slowed from the prior quarter.

AutoZone shares, which have risen nearly 10 percent in 2009 on expectations that the economic downturn was supporting sales of car parts as people held onto their vehicles longer, were down more than 5 percent in early trading.

Some analysts said AutoZone's results missed expectations slightly, but were largely in line, and others said they expected support for the auto-parts retail market overall and AutoZone as consumers continued driving their older cars.

Billionaire investor Edward Lampert held about a 37.6 percent stake in AutoZone as of mid-July. AutoZone said it bought back 3.8 million shares in the quarter for $587 million at an average price of $154 per share.

Goldman Sachs analyst Matthew Fassler said in a note that the result was likely to have a neutral to negative impact on AutoZone stock in the near term, and highlights the challenges of improving profitability off of a lofty base.

Net income fell to $236.1 million, or $4.43 per share, in the quarter that ended Aug. 29, from $243.7 million, or $3.88 per share, a year earlier.

Excluding expenses for an interest rate swap termination, AutoZone earned $4.47 per share in the quarter, while analysts on average expected $4.45 excluding one-time items, according to Reuters Estimates.

Sales rose 1 percent to just over $2.23 billion, slightly above the analysts' average forecast, which rounded upward to $2.23 billion.

The U.S. government cash for clunkers program, which provided incentives of up to $4,500 for drivers to turn in low-mileage vehicles and buy new, more fuel-efficient cars and trucks, had little impact on the retail auto-parts sector, analysts said.

Fourth-quarter results at AutoZone should allay some fears that topline is severely 'left behind' in economic recovery (or that 'clunkers' killed the sector), Stifel Nicolaus analyst David Schick said in a note to clients.

Schick said longer term, the retail auto-parts industry should be positive with Americans likely to retain cars longer over the next five years as they rebuild from the recession.

RBC Capital Markets Corp said the aftermarket parts retailers remained a favorite sector.

In our opinion, investors should have exposure to this retail sub-sector, especially if the slope of the recovery curve proves to be less steep than what most equity investors seem to believe right now, RBC analyst Scot Ciccarelli said in a note.

The quarter was 16 weeks this year and 17 weeks last year. Excluding the additional week last year, quarterly income was up 3.6 percent year over year, AutoZone said.

Sales at existing stores, a key measure in retail also referred to as same-store sales, rose 5.4 percent in the quarter, AutoZone said. Same-store sales had grown 7.4 percent in the third quarter.

Operating expenses as a percentage of sales were flat with a year earlier when excluding the extra week with increased sales largely offset by investments in its hub stores and an accelerated store maintenance program, AutoZone said.

AutoZone shares fell $7.74, or 5.1 percent, to $145.19 on the New York Stock Exchange. Through Tuesday, the stock was up 9.6 percent in 2009. (Reporting by David Bailey; Editing by Lisa Von Ahn and Maureen Bavdek)