diff --git a/rows.go b/rows.go
index d4f7a901..9dc66ac0 100644
--- a/rows.go
+++ b/rows.go
@@ -797,7 +797,7 @@ func computeNamedStructFields(
 			if !dbTagPresent {
 				colName = sf.Name
 			}
-			fpos := fieldPosByName(fldDescs, colName)
+			fpos := fieldPosByName(fldDescs, colName, !dbTagPresent)
 			if fpos == -1 {
 				if missingField == "" {
 					missingField = colName
@@ -816,13 +816,18 @@ func computeNamedStructFields(
 
 const structTagKey = "db"
 
-func fieldPosByName(fldDescs []pgconn.FieldDescription, field string) (i int) {
+func fieldPosByName(fldDescs []pgconn.FieldDescription, field string, replace bool) (i int) {
 	i = -1
+	if replace {
+		field = strings.ReplaceAll(field, "_", "")
+	}
 	for i, desc := range fldDescs {
 
 		// Snake case support.
-		field = strings.ReplaceAll(field, "_", "")
-		descName := strings.ReplaceAll(desc.Name, "_", "")
+		descName := desc.Name
+		if replace {
+			descName = strings.ReplaceAll(desc.Name, "_", "")
+		}
 
 		if strings.EqualFold(descName, field) {
 			return i
@@ -848,4 +853,4 @@ func setupStructScanTargets(receiver any, fields []structRowField) []any {
 		scanTargets[i] = v.FieldByIndex(f.path).Addr().Interface()
 	}
 	return scanTargets
-}
+}
\ No newline at end of file
diff --git a/rows_test.go b/rows_test.go
index 5dbf952d..5494725c 100644
--- a/rows_test.go
+++ b/rows_test.go
@@ -693,7 +693,7 @@ func TestRowToStructByNameDbTags(t *testing.T) {
 		// check missing fields in a returned row
 		rows, _ = conn.Query(ctx, `select 'Smith' as last_name, n as age from generate_series(0, 9) n`)
 		_, err = pgx.CollectRows(rows, pgx.RowToStructByName[person])
-		assert.ErrorContains(t, err, "cannot find field First in returned row")
+		assert.ErrorContains(t, err, "cannot find field first_name in returned row")
 
 		// check missing field in a destination struct
 		rows, _ = conn.Query(ctx, `select 'John' as first_name, 'Smith' as last_name, n as age, 'd5e49d3f' as account_id, '5e49d321' as account__id, null as ignore from generate_series(0, 9) n`)
@@ -992,4 +992,4 @@ insert into products (name, price) values
 	// Cheeseburger: $10
 	// Fries: $5
 	// Soft Drink: $3
-}
+}
\ No newline at end of file