The 2003–04 EHF Champions League was the 44th edition of Europe's premier club handball tournament. Montpellier Handball were the reigning champions. RK Celje won their first ever title, beating SG Flensburg-Handewitt in the final. This was the first time a Slovenian team won the tournament.

	Agg.		1st match	2nd match
HC Hard	61–43	Arkatron Minsk	35–17	26–26
Fiqas Aalsmeer	57–64	RK Bosna Sarajevo	21–29	36–35
HC Granitas Kaunas	46–58	Filippos Verias	26–33	20–25
Haukar Hafnarfjörður	57–47	CD de São Bernardo-Aveiro	37–23	20–24
Handballclub Tongeren	46–61	MŠK Považská Bystrica	25–26	21–35

Team	Pld	W	D	L	GF	GA	GD	Pts		LEM	BMC	ZTR	CON
TBV Lemgo	6	4	2	0	196	157	+39	10		—	34–29	27–27	41–22
BM Ciudad Real	6	4	1	1	187	145	+42	9		34–34	—	24–15	38–14
ZTR Zaporizhia	6	2	1	3	161	145	+16	5		22–28	25–30	—	31–24
Conversano	6	0	0	6	118	215	−97	0		23–32	23–32	12–41	—

Team	Pld	W	D	L	GF	GA	GD	Pts		SCM	BAR	HAU	VAR
SC Magdeburg	6	5	0	1	192	176	+16	10		—	34–29	27–27	41–22
FC Barcelona	6	4	1	1	203	152	+51	9		34–34	—	24–15	38–14
Haukar Hafnarfjörður	6	2	1	3	179	193	−14	5		22–28	25–30	—	31–24
Vardar Vatrost. Skopje	6	0	0	6	157	210	−53	0		23–32	23–32	12–41	—

Team	Pld	W	D	L	GF	GA	GD	Pts		KIF	P67	PAR	ASK
KIF Kolding	6	4	1	1	204	172	+32	9		—	42–32	42–26	37–27
Prule 67 Ljubljana	6	4	1	1	181	178	+3	9		31–25	—	29–29	31–28
Partizan	6	1	1	4	179	194	−15	3		30–31	32–33	—	35–30
ASKİ Ankara	6	1	1	4	163	183	−20	3		27–27	22–26	29–27	—

Pos	Team	Pld	W	D	L	GF	GA	GD	Pts
1	Montpellier HB	6	5	0	1	167	144	+23	15
2	CBM Ademar León	6	4	0	2	179	161	+18	12
3	Medwedi Tschechow	6	3	0	3	166	165	+1	9
4	HC Hard	6	0	0	6	138	180	−42	0

Pos	Team	Pld	W	D	L	GF	GA	GD	Pts
1	RK Zagreb	6	3	0	3	159	144	+15	9
2	SC Szeged	6	3	0	3	160	154	+6	9
3	Sandefjord TIF	6	3	0	3	149	157	−8	9
4	Filippos Verias	6	3	0	3	154	167	−13	9

Pos	Team	Pld	W	D	L	GF	GA	GD	Pts
1	RK Celje	6	5	1	0	196	161	+35	16
2	SG Flensburg-Handewitt	6	4	1	1	211	181	+30	13
3	Redbergslids IK	6	2	0	4	179	186	−7	6
4	MŠK Považská Bystrica	6	0	0	6	163	221	−58	0

Pos	Team	Pld	W	D	L	GF	GA	GD	Pts
1	KC Veszprém	6	6	0	0	197	156	+41	18
2	Skjern Handball	6	2	1	3	151	153	−2	7
3	KS Kielce	6	2	1	3	159	177	−18	7
4	HC Bosna Sarajevo	6	1	0	5	151	172	−21	3

Pos	Team	Pld	W	D	L	GF	GA	GD	Pts
1	Chambéry Savoie HB	6	6	0	0	185	157	+28	18
2	Pfadi Winterthur	6	2	1	3	192	178	+14	7
3	HC Baník Karviná	6	2	0	4	180	194	−14	6
4	RK Metković	6	1	1	4	156	184	−28	4

Team #1	Team #2	1st match	2nd match	Agg.
BM Ciudad Real	Chambéry Savoie HB	36–28	33–32	69–60
Skjern Handball	SC Magdeburg	30–25	24–34	54–59
CBM Ademar León	RK Celje	38–25	21–34	59–59*
SG Flensburg-Handewitt	Kolding KIF	34–29	33–20	67–49
SC Szeged	Montpellier HB	29–22	26–27	55–49
Pfadi Winterthur	RK Zagreb	32–29	24–32	56–61
Prule 67 Ljubljana	TBV Lemgo	28–28	27–32	55–60
FC Barcelona	KC Veszprém	33–29	26–31	59–60

Team #1	Team #2	1st match	2nd match	Agg.
SG Flensburg-Handewitt	RK Zagreb	30–27	28–26	58–53
SC Szeged	SC Magdeburg	30–31	24–28	54–59
RK Celje	TBV Lemgo	32–25	28–28	60–53
BM Ciudad Real	KC Veszprém	33–24	28–25	61–49

Team #1	Team #2	1st match	2nd match	Agg.
BM Ciudad Real	RK Celje	35–36	32–34	67–70
SG Flensburg-Handewitt	SC Magdeburg	30–20	26–36	56–56*

Team #1	Team #2	1st match	2nd match	Agg.
RK Celje	SG Flensburg-Handewitt	34–28	28–30	62–58

• EHF Champions League website