Marriage Dissolution rate is on the rise world-wide! This study therefore assessed factors responsible for marriage dissolution such as: Desertion, Cruelty, Adultery, Infidelity, In-Human Behaviour and In-Ability to Consummate Marriage; and its trend in Oyo State. A case study on Oyo State was carried out. Data was gleaned from case files on marriage dissolutions in Oyo State, from (1985-2007). Descriptive, Time Series and Regression Statistics were used to analyse data obtained. Results obtained from the Descriptive Statistics showed that Infidelity is the main reason (factor) for marriage dissolution. The TREND showed that Adultery and In-Human Behaviour are factors highly responsible for marriage dissolution. Graphical representations revealed that the rate at which Desertion influenced marriage dissolution was low in 1985, while it was at its highest rate in 1998. The Significance between Number of Dissolved Marriages and Adultery was very high; about 95%, and the strength of association between Number of Dissolved Marriages and In-Human Behaviour was also about 95% - this shows that several marriages are dissolved due to Adultery and In-Human Behaviour.