The SalesRank response group provides the sales rank for each item in the response.
Sample Response (REST)
<?xml version="1.0" encoding="UTF-8"?>
<ItemLookupResponse xmlns="http://webservices.amazon.com/AWSECommerceService/2005-03-23">
<OperationRequest>
<HTTPHeaders>
<Header Name="UserAgent" Value="Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)"/>
</HTTPHeaders>
<RequestId>1ZX2J0H6SZ35XNSNS77X</RequestId>
<Arguments>
<Argument Name="Service" Value="AWSECommerceService"/>
<Argument Name="AssociateTag" Value="[Your Associate ID Here]"/>
<Argument Name="SubscriptionId" Value="[Your Subscription ID Here]"/>
<Argument Name="ItemId" Value="0060006781"/>
<Argument Name="ResponseGroup" Value="SalesRank"/>
<Argument Name="Operation" Value="ItemLookup"/>
</Arguments>
</OperationRequest>
<Items>
<Request>
<IsValid>True</IsValid>
</Request>
<Item>
<ASIN>0060006781</ASIN>
<SalesRank>4,107</SalesRank>
</Item>
</Items>
</ItemLookupResponse>
The Request that Generated the Response (REST)
http://webservices.amazon.com/onca/xml?Service=AWSECommerceService
&SubscriptionId=[Your Subscription ID Here]
&AssociateTag=[Your Associate ID Here]
&Operation=ItemLookup
&IdType=
ASIN&ItemId=0060006781&ResponseGroup=SalesRank