The Corruption Perception Index is produced by Transparency International, a global civil society organisation focused on fighting corruption. It ranks countries based on how corrupt their public sector is perceived to be. The index is measured on a scale of 0 to 10 with a score of 0 being "highly corrupt" and 10 being "very clean".
Nigeria ranked 143 out of 183 countries with a score of 2.4. Though its position changed to 143 from 134 in 2010 (probably due to an increase in the number of countries assessed this year), its CPI score (2.4) remained the same as last year. In the last five years, Nigeria has performed badly in the Corruption Perception Index. In 2009, Nigeria ranked 130 with a CPI score of 2.5. In 2008, it ranked 121 with a CPI score of 2.7. See below a summary of Nigeria’s performance since 2007:
| Year | Rank | Score |
| 2007 | 147 (out of 179 countries) | 2.2 |
| 2008 | 121 (out of 180 countries) | 2.7 |
| 2009 | 130 (out of 180 countries) | 2.5 |
| 2010 | 134 (out f 178 countries) | 2.4 |
| 2011 | 143 (out of 183 countries) | 2.4 |
In Sub-Sahara Africa, Botswana ranked the best at 32 with a CPI score of 6.1, while Cape Verde ranked the best in the West African region with a position of 41 and a CPI score of 5.5. Ghana ranked 69 with a CPI score of 3.9 making it the ‘second best’ ranking country in West Africa. Guinea was the worst ranked West African country at 164 with a CPI score of 2.1.
Performance of West African Countries in the 2011 Corruption Perception Index
| Country | Rank | Score |
| Cape Verde | 41 | 5.5 |
| Ghana | 69 | 3.9 |
| Gambia | 77 | 3.5 |
| Liberia | 91 | 3.2 |
| Benin | 100 | 3 |
| Burkina Faso | 100 | 3 |
| Senegal | 112 | 2.9 |
| Mali | 118 | 2.8 |
| Niger | 134 | 2.5 |
| Sierra Leone | 134 | 2.5 |
| Mauritania | 143 | 2.4 |
| Nigeria | 143 | 2.4 |
| Togo | 143 | 2.4 |
| Cote d’Ivoire | 154 | 2.2 |
| Guinea Bissau | 154 | 2.2 |
| Guinea | 164 | 2.1 |
