The following is a list of all of the heart pieces in The Legend of Zelda: Oracle of Ages, along with their locations. They are listed in order based on how soon you can get them in the game.

Pieces of Heart

1. Maple

Item(s) required: None
Description: Every time you defeat 30 enemies (or 15 if you are wearing the Maple Ring), Maple will appear in some overworld areas, flying past on a broom or other object. Bump into her and she will drop a bunch of items. Sometimes she drops a Piece of Heart. It's random. After you get a Heart Piece from her, she won't drop any more.

2. Gasha Trees

Item(s) required: Gasha Seed
Description: There are patches of soft soil in certain places in the overworld. If you have a Gasha Seed, you can plant it in soft soil. After you defeat a certain number of enemies, the Gasha Seed becomes a Gasha Tree, with a Gasha Nut on it. Use your sword to knock the nut down. There will be a random item inside. You can increase the rarity of the item by defeating more enemies before opening the nut, planting the tree in a hard-to-reach place, and wearing the Gasha Ring. There is a chance that the item in the nut will be a Piece of Heart. After you get a Heart Piece from a Gasha Nut, you won't get any more from Gasha Nuts.

3. Black Tower (Past)

Item(s) required: Shovel
Description: After getting the shovel from a worker in the Black Tower near the beginning of the game, outside of the Black Tower entrance and use the shovel to reach the Heart Piece.

4. Maku Path (Past)

Item(s) required: Shovel
Description: There is a Piece of Heart in plain sight in a room of the Maku Path in the past. To get it, push the leftmost block up, then push the block next to you to the right.

5. Yoll Graveyard (Present)

Item(s) required: Power Bracelet
Description: In the southwest corner of Yoll Graveyard, the Heart Piece is in plain sight. Use the Power Bracelet (from Spirit's Tomb) to lift the rock and reach the Piece of Heart.

6. Deku Forest (Past)

Item(s) required: Ember Seed
Description: The Deku Forest is in the past. You first enter it after the entrance to Wing Dungeon crumbles in the present day. The Wing Dungeon is still standing in the past, but it's entrance is sealed up and you need to find bombs. Go toward the southwest corner of the forest. There is a small tree in the corner of some larger trees. Burn it with an Ember Seed and go down the stairs that appear. You will find a Heart Piece.

7. Talus Peaks (Past)

Item(s) required: Roc's Feather, Power Bracelet
Description: After getting the Roc's Feather, exit the Deku Forest and go north into the Talus Peaks. Keep going north until you find a cave entrance. Go in and use the Roc's Feather and Power Bracelet to reach the Piece of Heart.

8. Talus Peaks (Present)

Item(s) required: Tune of Currents
Description: After you learn the Tune of Currents, go south from the watery area, then go west across some shallow water and stand in the southwest corner of the screen. Play the Tune of Currents, then go east to get the Heart Piece.

9. Lynna City (Present)

Item(s) required: 500 Rupees, Tune of Currents
Description: Go to Lynna Village in the past, to the screen where the item shop is in present day Lynna City. Stand just above the tree that sticks out and play the Tune of Currents. If you were standing in the correct place, you will end up inside of a fence where you can reach another door in the item shop building. Go into this door and go downstairs to buy a Piece of Heart for 500 rupees.

10. Rolling Ridge (Present)

Item(s) required: Bomb
Description: Go south one screen from the Great Moblin's Tower, then west one screen. Go into the cave entrance and use a bomb on the wall to reach the Heart Piece.

11. Rolling Ridge (Present)

Item(s) required: Tune of Currents
Description: Start at the waterfall entrance to Mermaid's Cave in the past. Go west, then north. Go into the cave and go through it until you're outside again. Go east and cut through the bushes until you are in the bottom-right corner. Play the Tune of Currents and go get the Piece of Heart that is out in the open.

12. Crescent Island (Present)

Item(s) required: Mermaid Suit
Description: Go to Crescent Island in the present day. Get in the water and swim along the north coast of the island, then dive into the water. Swim east along the northern coast until you find a passageway under the island. Go south until you reach a screen with a whirlpool, then go west, then south, then west, then north until you reach a cave entrance. Go into the cave and get the Heart Piece from the chest.