以下是我从MSDN中翻译过来的三个Delphi单元，调用任意一个单元中声明的API都可以获取网卡的物理地址，但三个单元中的API函数的有效环境和功能各有不同，我把说明附于代码的注释中。
unit Lmwksta;
interface
uses
Windows,SysUtils,Dialogs;
type
_WKSTA_TRANSPORT_INFO_0=packed record
wkti0_quality_of_service:DWORD;
wkti0_number_of_vcs:DWORD;
wkti0_transport_name:PWideChar;{连接设备名称，这个名称是\DEVICE\NetBT_TcpIp……我也不知道如何理解，不过我们只想获取MAC地址就不必管它了！}
wkti0_transport_address:PWideChar; //MAC地址
wkti0_wan_ish:BOOL; //是否是广域网连接
end;
WKSTA_TRANSPORT_INFO_0=_WKSTA_TRANSPORT_INFO_0;
PWKSTA_TRANSPORT_INFO_0=^WKSTA_TRANSPORT_INFO_0;
const
NERR_Success=0;
MAX_PREFERRED_LENGTH=$FFFFFFFF;
//当本计算机有可用的网卡，且已经连接上网络时，调用本函数才能成功，否则获取不到任何信息
function NetWkstaTransportEnum(
ServerName:PWideChar;//主机名称，传递nil时表示本机
Level:DWORD;//传递0
BufPtr:PPointer; {接受_WKSTA_TRANSPORT_INFO_0记录数组的缓冲区，有此函数自行分配，但使用完后要用下面定义的NetApiBufferFree函数释放内存}
PrefMaxLen:DWORD;//缓冲区最大长度，传递上面定义的MAX_PREFERRED_LENGTH常量即可
EntriesRead,TotalEntries,ResumeHandle:PDWORD):DWORD;stdcall;
{EntriesRead为返回的_WKSTA_TRANSPORT_INFO_0记录数组的元素个数,至于TotalEntries和ResumeHandle，可以传递nil，需要更深入的了解，请参见MSDN}
function NetApiBufferFree(Buffer:Pointer):DWORD;stdcall;
implementation
function NetWkstaTransportEnum;external 'netapi32.dll' name 'NetWkstaTransportEnum';
function NetApiBufferFree;external 'netapi32.dll' name 'NetApiBufferFree';
end.
unit Rpcdce;
interface
uses
Windows,SysUtils;
type
TUUID=packed record
Data1:ULONG;
Data2:Word;
Data3:Word;
Data4:array [0..7] of Byte;//此数组的后6个元素就是网卡的物理地址信息
end;
TGUID=TUUID;
PUUID=^TUUID;
const
{以下为UuidCreateSequential函数的可能返回值}
RPC_S_UUID_LOCAL_ONLY:LongInt=1824; //函数生成的GUID只能保证在本计算机上是唯一的
RPC_S_UUID_NO_ADDRESS:LongInt=1739; //不能获取以太网或令牌环网网卡设备
RPC_S_OK:LongInt=0; //函数调用成功，生成的GUID中包含了网卡的物理地址信息
function UuidCreateSequential(var uuid:TUUID):Cardinal;stdcall; //此函数只使用于单网卡的机器
function GetMACAddress:string;
implementation
function UuidCreateSequential;external 'Rpcrt4.dll' name 'UuidCreateSequential';
//引用此单元后，只需要调用GetMACAddress函数即可获得网卡物理地址
function GetMACAddress:string;
var
uuid:TUUID;
I:Integer;
begin
Result:='';
if UuidCreateSequential(uuid)=RPC_S_OK then
for I:=2 to 7 do
begin
if I>2 then Result:=Result+'-';
Result:=Result+IntToHex(uuid.Data4[I],2);
end;
end;
end.
unit IPHlpAPI;
interface
uses
Windows,SysUtils,Classes;
const
MAX_ADAPTER_DESCRIPTION_LENGTH=128;
MAX_ADAPTER_NAME_LENGTH=256;
MAX_ADAPTER_ADDRESS_LENGTH=8;
DEFAULT_MINIMUM_ENTITIES=32;
MAX_HOSTNAME_LEN=128;
MAX_DOMAIN_NAME_LEN=128;
MAX_SCOPE_ID_LEN=256;
ERROR_NO_DATA:LongInt=232;
ERROR_NOT_SUPPORTED:LongInt=50;
ERROR_INVALID_PARAMETER:LongInt=87;
ERROR_BUFFER_OVERFLOW:LongInt=111;
type
time_t=Integer;
IP_ADDRESS_STRING=packed record
Addr:array [0..15] of Char;
end;
PIP_ADDRESS_STRING=^IP_ADDRESS_STRING;
IP_MASK_STRING=IP_ADDRESS_STRING;
PIP_MASK_STRING=^IP_MASK_STRING;
PIPAdapterInfo=^TIPAdapterInfo;
TIPAdapterInfo=packed record
Next:PIPAdapterInfo;//下一个节点的指针
ComboIndex:DWORD;
AdapterName:array [0..MAX_ADAPTER_NAME_LENGTH + 3] of Char; //适配器名称
Description:array [0..MAX_ADAPTER_DESCRIPTION_LENGTH + 3] of Char; //适配器描述信息
AddressLength:UINT;//Address域的最大长度,传递MAX_ADAPTER_ADDRESS_LENGTH常量即可
Address:array [0..MAX_ADAPTER_ADDRESS_LENGTH-1] of Byte;//适配器物理地址
Index:DWORD;
uType:UINT;
DhcpEnabled:UINT;
CurrentIpAddress:PIP_ADDRESS_STRING;
IpAddressList:IP_ADDRESS_STRING;
GatewayList:IP_ADDRESS_STRING;
DhcpServer:IP_ADDRESS_STRING;
HaveWins:BOOL;
PrimaryWinsServer:IP_ADDRESS_STRING;
SecondaryWinsServer:IP_ADDRESS_STRING;
LeaseObtained:time_t;
LeaseExpires:time_t;
end;
//此函数功能最强大，而且只要求网卡在系统中可用，并不要求一定连接上网络
function GetAdaptersInfo(Buf:PIPAdapterInfo;var BufLen:ULONG):DWORD;stdcall;
implementation
function GetAdaptersInfo;external 'iphlpapi.dll' name 'GetAdaptersInfo';
end.
对于GetAdaptersInfo函数，Buf参数要求函数的调用者自行分配，如果分配的空间不足，函数返回ERROR_BUFFER_OVERFLOW，BufLen变参的值被设置为实际需要的缓冲区大小，因此可以再行分配，以满足需
求,采用链表遍历操作可以获取所有已安装网卡的物理地址。
本文来自Delphi之窗，原文地址：http://www.52delphi.com