new file mode 100644
--- /dev/null
+++ b/contrib/bash_completion
@@ -0,0 +1,129 @@
+_hg_commands()
+{
+    local commands="$(hg -v help | sed -e '1,/^list of commands:/d' \
+                                       -e '/^global options:/Q' \
+				       -e '/^ [^ ]/!d; s/[,:]//g;')"
+    
+    # hide debug commands from users, but complete them if 
+    # specifically asked for
+    if [[ "$cur" == de* ]]; then
+	commands="$commands debugcheckstate debugstate debugindex"
+	commands="$commands debugindexdot debugwalk"
+    fi
+    COMPREPLY=( ${COMPREPLY[@]:-} $(compgen -W "$commands" -- "$cur") )
+}
+
+_hg_paths()
+{
+    local paths="$(hg paths | sed -e 's/ = .*$//')"
+    COMPREPLY=(${COMPREPLY[@]:-} $( compgen -W "$paths" -- "$cur" ))
+}
+
+_hg_tags()
+{
+    local tags="$(hg tags | sed -e 's/[0-9]*:[a-f0-9]\{40\}$//; s/ *$//')"
+    COMPREPLY=( ${COMPREPLY[@]:-} $(compgen -W "$tags" -- "$cur") )
+}
+
+# this is "kind of" ugly...
+_hg_count_non_option()
+{
+    local i count=0
+    local filters="$1"
+
+    for (( i=1; $i<=$COMP_CWORD; i++ )); do
+	if [[ "${COMP_WORDS[i]}" != -* ]]; then
+	    for f in $filters; do
+		if [[ ${COMP_WORDS[i-1]} == $f ]]; then
+		    continue 2
+		fi
+	    done
+	    count=$(($count + 1))
+	fi
+    done
+
+    echo $(($count - 1))
+}
+
+_hg()
+{
+    local cur prev cmd opts i
+
+    COMPREPLY=()
+    cur="$2"
+    prev="$3"
+
+    # searching for the command 
+    # (first non-option argument that doesn't follow -R/--repository)
+    for (( i=1; $i<=$COMP_CWORD; i++ )); do
+	if [[ ${COMP_WORDS[i]} != -* ]] \
+	   && [ "${COMP_WORDS[i-1]}" != -R ] \
+	   && [ "${COMP_WORDS[i-1]}" != --repository ]; then
+	    cmd="${COMP_WORDS[i]}"
+	    break
+	fi
+    done
+
+    if [[ "$cur" == -* ]]; then
+	opts="$(hg -v help | sed -e '1,/^global options/d; /^ -/!d')"
+
+	if [ -n "$cmd" ]; then
+	    opts="$opts $(hg help "$cmd" | sed -e '/^ -/!d; s/ [^-][^ ]*//')"
+	fi
+
+	COMPREPLY=( ${COMPREPLY[@]:-} $(compgen -W "$opts" -- "$cur") )
+	return
+    fi
+
+    if [ "$prev" = -R ] || [ "$prev" = --repository ]; then
+        COMPREPLY=(${COMPREPLY[@]:-} $( compgen -d -- "$cur" ))
+	return
+    fi
+
+    if [ -z "$cmd" ] || [ $COMP_CWORD -eq $i ]; then
+	_hg_commands
+	return
+    fi
+
+    if [ "$cmd" != status ] && [ "$prev" = -r ] || [ "$prev" = --rev ]; then
+	_hg_tags
+	return
+    fi
+
+    case "$cmd" in
+	help)
+	    _hg_commands
+	;;
+	export|manifest|update|checkout|up|co)
+	    _hg_tags
+	;;
+	pull|push)
+	    _hg_paths
+	    COMPREPLY=(${COMPREPLY[@]:-} $( compgen -d -- "$cur" ))
+	;;
+	paths)
+	    _hg_paths
+	;;
+	clone)
+	    local count=$(_hg_count_non_option)
+	    if [ $count = 1 ]; then
+		_hg_paths
+	    fi
+	    COMPREPLY=(${COMPREPLY[@]:-} $( compgen -d -- "$cur" ))
+	;;
+	cat)
+	    local count=$(_hg_count_non_option -o --output)
+	    if [ $count = 2 ]; then
+		_hg_tags
+	    else
+		COMPREPLY=(${COMPREPLY[@]:-} $( compgen -f -- "$cur" ))
+	    fi
+	;;
+	*) 
+            COMPREPLY=(${COMPREPLY[@]:-} $( compgen -f -- "$cur" ))
+	;;
+    esac
+
+}
+
+complete -o filenames -F _hg hg