The purpose of this research was to evaluate the agronomic effectiveness of rock phosphate, biological fertilizers (Rhizobium and bio-phosphate) and their combinations on dry matter (DM) production, nutrient content and in vitro dry matter digestibility (IVDMD) of Stylosanthes guianensis CIAT 184. This research was conducted at Forage and Pasture Laboratory, Universitas Gadjah Mada, Yogyakarta, Indonesia from February -October 2010. A strip plot design which consisted of two fertilizer factors with three (3) replicates was used. The first factor was the horizontal factor and consisted of four levels of biological fertilizers (Rhizobium and bio-phosphate) namely: M 0 = control, M 1 = Rhizobium (0.5 g/plot), M 2 = bio-phosphate (0.6 g/plot) and M 3 = combinations of Rhizobium and bio-phosphate. The second factor was the vertical factor and consisted of three levels of rock phosphate, namely: P 0 = control, P 1 = 250 kg/ha (32.5 P kg/ha) and P 2 = 500 kg/ha (65 P kg/ha). Defoliation was carried out every three months for 9 months. Results of the study showed that there was no significant difference in DM production (kg/ha) amongst treatments. Although the current research showed no significance difference amongs the treatments, DM production increased in the 2 nd harvest (12.3%) and 4 th harvest (7.1%) between P 0 and P 1 . Combinations treatment P 1 M 2 (21073.63 kg/ha) had the highest average DM production amongs treatments. Statistical analysis followed by Duncan's new Multiple Range Test (DMRT), showed that rock phosphate can significantly (P<0.05) increase fiber production of Stylosanthes guianensis. It showed that treatment P 1 increased crude fiber production by 12.2% from 5864, 47 kg/ha to 6580,19 kg/ha. In addition, tests further revealed that there was a difference between M 1 and M 2 , but had no effect on M 0 . There was no significant effect on production (kg/ha) of crude protein, phosphorus, nitrogen free extract (NFE) and ash. In conclusion, treatments with rock phosphate and bio-fertilizers tend to increase productivity of Stylosanthes guianensis CIAT 184.