Several Indian states have achieved or on the way of achieving the replacement level fertility, but the performance of Bihar are far from this. Accordingly, this paper attempts to assess the level and trends of fertility in across districts of fertility and its future prospect. Results shows that TFR is slow decline among districts but yet some districts have high TFR and substantial differences across the socio-economic groups. Contraceptive prevalence rate is marginal differs across the socio-economic groups in the state. Result of Gompertz Model indicates that rate of decline in TFR is decelerate after 1997, Low literacy, Low urbanization preceding poverty are may be other important factors, which may be the cause for decelerate. The projection of result indicates that at present projected TFR for the state is 3.66 (2010), which is far away from target of achieve to replacement of fertility till 2010 by national policy agenda. Moreover the pace of fertility decline seems very slow in coming years. For instance, in 2020 it will reach at the level 2.8 and by 2030 it will reduced only up to 2.2. After very long (2035) time, TFR of the state will achieve at replacement level. The Government’s intervention should focus more first is the local level need based planning for family welfare programmes.