Cameroon has great assets for the production of rice in large quantities. But to achieve this, it is undeniable to advocate intensive rice cultivation. To achieve this, it is important to control the timing of the application of bottom dressing fertilizer (NPK) in order to increase the production of this foodstuff. The objective of this work was to determine the optimal time of application of bottom dressing (NPK) for maximum yield of rainfed rice. A trial was conducted in Yaoundé (Cameroon) using a one-factor Latin square design with three application times of the basal fertilizer (NPK) as treatments: at sowing (T0), at 10 days after emergence (T10) and 20 days after emergence (T20) and three replications. Growth parameters, yield components, material production and yield were evaluated. The results obtained indicate non-significant differences for growth and yield parameters but significant differences are detected for biomass.