This is a list of 57 member states of the Organisation of Islamic Cooperation sorted by their estimated population.

Population

Rank	Country	Total Population (all religions)
1	Indonesia	268,074,600
2	Pakistan	212,742,631
3	Nigeria	193,392,517
4	Bangladesh	166,290,000
5	Egypt	98,467,400
6	Iran	82,321,600
7	Turkey	82,003,882
8	Algeria	43,378,027
9	Sudan	41,394,625
10	Iraq	39,127,900
11	Morocco	34,974,200
12	Uganda	40,006,700
13	Saudi Arabia	33,413,660
14	Uzbekistan	33,412,688
15	Malaysia	32,666,700
16	Afghanistan	31,575,018
17	Yemen	29,579,986
18	Mozambique	28,861,863
19	Ivory Coast	25,823,071
20	Cameroon	24,348,251
21	Niger	22,314,743
22	Burkina Faso	20,870,060
23	Mali	19,973,000
24	Syria	18,499,181
25	Kazakhstan	18,446,552
26	Senegal	16,209,125
27	Chad	15,692,969
28	Somalia	15,636,171
29	Guinea	12,218,357
30	Benin	11,733,059
31	Tunisia	11,551,448
32	Jordan	10,381,500
33	Azerbaijan	9,981,457
34	United Arab Emirates	9,682,088
35	Tajikistan	8,931,000
36	Sierra Leone	7,901,454
37	Togo	7,538,000
38	Libya	6,569,864
39	Kyrgyzstan	6,389,500
40	Lebanon	6,065,922
41	Turkmenistan	5,634,555
42	Palestine	4,780,978
43	Oman	4,672,823
44	Kuwait	4,226,920
45	Mauritania	4,077,347
46	Albania	2,862,427
47	Qatar	2,772,947
48	Gambia	2,228,075
49	Gabon	2,109,099
50	Guinea-Bissau	1,604,528
51	Bahrain	1,543,300
52	Djibouti	1,078,373
53	Comoros	873,724
54	Guyana	786,508
55	Suriname	573,085
56	Maldives	427,756
57	Brunei	421,300
	Total (all religions)	1,810,399,070

Muslim population

8 countries- Benin, Cameroon, Gabon, Guyana, Mozambique, Suriname, Togo and Uganda are not Muslim-majority, but they are members of Organisation of Islamic Cooperation.

Member state	Percentage Muslim[1]
Afghanistan	99.0% plus
Albania	56.00%
Algeria	97.90%
Azerbaijan	96.90%
Bahrain	70.30%
Bangladesh	89.80%
Benin	23.80%
Brunei	75.10%
Burkina Faso	61.60%
Cameroon	18.30%
Chad	55.30%
Comoros	98.30%
Cote d'Ivoire	37.50%
Djibouti	96.90%
Egypt	94.90%
Gabon	11.20%
Gambia	95.10%
Guinea	84.40%
Guinea Bissau	50.00%
Guyana	6.4% approx.
Indonesia	87.20%
Iran	99.0% plus
Iraq	99.00%
Jordan	97.20%
Kazakhstan	70.40%
Kuwait	74.10%
Kyrgyzstan	88.00%
Lebanon	61.30%
Libya	96.60%
Malaysia	63.70%
Maldives	98.40%
Mali	92.40%
Mauritania	99.0% plus
Morocco	99.0% plus
Mozambique	18.00%
Niger	98.40%
Nigeria	50.40%
Oman	85.90%
Pakistan	96.40%
Palestinian territories	97.60%
Qatar	67.70%
Saudi Arabia	93.00%
Senegal	96.40%
Sierra Leone	78.00%
Somalia	99.0% plus
Sudan	90.70%
Suriname	13.90%
Syria	92.80%
Tajikistan	96.70%
Togo	14.00%
Tunisia	99.0% plus
Turkey	98.00%
Turkmenistan	93.00%
Uganda	11.50%
United Arab Emirates	76.90%
Uzbekistan	96.70%
Yemen	99.0% plus