Doubles
2018 Croatia Open Umag
Final
Champions	Robin Haase Matwé Middelkoop
Runners-up	Roman Jebavý Jiří Veselý
Score	6–4, 6–4
Events
Singles Doubles
← 2017 · Croatia Open Umag · 2019 →

Guillermo Durán and Andrés Molteni were the defending champions, but Durán chose not to participate and Molteni chose to compete in Båstad instead.

Robin Haase and Matwé Middelkoop won the title, defeating Roman Jebavý and Jiří Veselý in the final, 6–4, 6–4.

	First round							Quarterfinals							Semifinals							Final
	1	D Inglot F Škugor	79	6
		S Arends T-S Weissborn	67	4				1	D Inglot F Škugor	4	6	[10]
		M Marterer H Podlipnik-Castillo	6	6					M Marterer H Podlipnik-Castillo	6	2	[5]
		M Cecchinato A Ramos Viñolas	3	4											1	D Inglot F Škugor	4	4
	4	J Eysseric H Nys	65	4												R Jebavý J Veselý	6	6
		D Molchanov I Zelenay	77	6					D Molchanov I Zelenay	3	5
		R Jebavý J Veselý	6	5	[10]				R Jebavý J Veselý	6	7
	WC	I Sabanov M Sabanov	4	7	[8]																		R Jebavý J Veselý	4	4
		P Lorenzi G Pella	6	6																		2	R Haase M Middelkoop	6	6
	WC	M Draganja T Draganja	3	1					P Lorenzi G Pella	2	7	[7]
		S González J Sousa	6	7					S González J Sousa	6	5	[10]
	3	A Šančić A Vasilevski	4	5												S González J Sousa	4	4
		R Arneodo B Paire	6	77											2	R Haase M Middelkoop	6	6
	Alt	N Jarry R Quiroz	2	64					R Arneodo B Paire	3	5
		D Lajović A Rublev	4	4				2	R Haase M Middelkoop	6	7
	2	R Haase M Middelkoop	6	6

• Main Draw