diff --git a/ObsoleteFiles.inc b/ObsoleteFiles.inc
--- a/ObsoleteFiles.inc
+++ b/ObsoleteFiles.inc
@@ -51,6 +51,9 @@
 #   xargs -n1 | sort | uniq -d;
 # done
 
+# 20240729: retire ifaddr_byindex
+OLD_FILES+=usr/share/man/man9/ifaddr_byindex.9.gz
+
 # 20240721: retire vm_page_alloc_freelist
 OLD_FILES+=usr/share/man/man9/vm_page_alloc_freelist.9.gz
 OLD_FILES+=usr/share/man/man9/vm_page_alloc_freelist_domain.9.gz
diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -1336,7 +1336,6 @@
 	ifnet.9 ifa_ifwithnet.9 \
 	ifnet.9 ifa_ref.9 \
 	ifnet.9 ifaddr.9 \
-	ifnet.9 ifaddr_byindex.9 \
 	ifnet.9 ifaof_ifpforaddr.9 \
 	ifnet.9 ifioctl.9 \
 	ifnet.9 ifpromisc.9 \
diff --git a/share/man/man9/ifnet.9 b/share/man/man9/ifnet.9
--- a/share/man/man9/ifnet.9
+++ b/share/man/man9/ifnet.9
@@ -75,8 +75,6 @@
 .\"
 .Ss "Interface Address Functions"
 .Ft "struct ifaddr *"
-.Fn ifaddr_byindex "u_short idx"
-.Ft "struct ifaddr *"
 .Fn ifa_ifwithaddr "struct sockaddr *addr"
 .Ft "struct ifaddr *"
 .Fn ifa_ifwithdstaddr "struct sockaddr *addr" "int fib"
@@ -196,8 +194,6 @@
 .Xr link_addr 3 )
 describing the link layer implemented by the interface (if any)
 is accessed by the
-.Fn ifaddr_byindex
-function or
 .Va if_addr
 structure.
 (Some trivial interfaces do not provide any link layer addresses;
@@ -1183,9 +1179,7 @@
 (A pointer to
 this address structure is saved in the
 .Vt ifnet
-structure and is accessed by the
-.Fn ifaddr_byindex
-function.)
+structure.)
 The
 .Fa ifp
 must have been allocated by
@@ -1502,10 +1496,6 @@
 .Fa addr
 will be returned.
 .Pp
-.Fn ifaddr_byindex
-returns the link-level address of the interface with the given index
-.Fa idx .
-.Pp
 All of these functions return a null pointer if no such address can be
 found.
 .Ss "Interface Multicast Address Functions"