diff --git a/R-package/R/xgb.DMatrix.R b/R-package/R/xgb.DMatrix.R
index a6b04a6b6..8b589f0d4 100644
--- a/R-package/R/xgb.DMatrix.R
+++ b/R-package/R/xgb.DMatrix.R
@@ -163,8 +163,11 @@ dimnames.xgb.DMatrix <- function(x) {
 #'     \item \code{weight}: to do a weight rescale ;
 #'     \item \code{base_margin}: base margin is the base prediction Xgboost will boost from ;
 #'     \item \code{nrow}: number of rows of the \code{xgb.DMatrix}.
+#'     
 #' }
 #' 
+#' \code{group} can be setup by \code{setinfo} but can't be retrieved by \code{getinfo}.
+#' 
 #' @examples
 #' data(agaricus.train, package='xgboost')
 #' train <- agaricus.train
@@ -214,7 +217,7 @@ getinfo.xgb.DMatrix <- function(object, name, ...) {
 #'     \item \code{label}: label Xgboost learn from ;
 #'     \item \code{weight}: to do a weight rescale ;
 #'     \item \code{base_margin}: base margin is the base prediction Xgboost will boost from ;
-#'     \item \code{group}.
+#'     \item \code{group}: number of rows in each group (to use with \code{rank:pairwise} objective).
 #' }
 #' 
 #' @examples
diff --git a/R-package/man/getinfo.Rd b/R-package/man/getinfo.Rd
index 480ef6b3e..7c666b7bf 100644
--- a/R-package/man/getinfo.Rd
+++ b/R-package/man/getinfo.Rd
@@ -27,7 +27,10 @@ The \code{name} field can be one of the following:
     \item \code{weight}: to do a weight rescale ;
     \item \code{base_margin}: base margin is the base prediction Xgboost will boost from ;
     \item \code{nrow}: number of rows of the \code{xgb.DMatrix}.
+    
 }
+
+\code{group} can be setup by \code{setinfo} but can't be retrieved by \code{getinfo}.
 }
 \examples{
 data(agaricus.train, package='xgboost')
diff --git a/R-package/man/setinfo.Rd b/R-package/man/setinfo.Rd
index e6cf3257f..e133d3a15 100644
--- a/R-package/man/setinfo.Rd
+++ b/R-package/man/setinfo.Rd
@@ -28,7 +28,7 @@ The \code{name} field can be one of the following:
     \item \code{label}: label Xgboost learn from ;
     \item \code{weight}: to do a weight rescale ;
     \item \code{base_margin}: base margin is the base prediction Xgboost will boost from ;
-    \item \code{group}.
+    \item \code{group}: number of rows in each group (to use with \code{rank:pairwise} objective).
 }
 }
 \examples{