The planting unit mechanisms of a Japanese rice transplanter was developed to suit narrow row spacing (20 cm)  and to agree with technical recommendations for rice cultivation in Egypt (RRTC, 2001). The development included proper modifications of fingers, and cross-feed stroke mechanisms, seedlings tray ,and the supporting floats. The developed transplanter was tested under different operating speeds ( 6.98, 7.85 and 8.96 m/s) to get different spaces under actual field conditions. The investigated machine was evaluated in terms of : the transplanting efficiency, the uniformity of hill distribution, and crop yield. The results showed that: Lowest defective hills percentage (4.3 %) and the highest distribution uniformity of lateral space (99 %) was achieved as  the developed machine at finger speed of 6.98 m/s. That may be compare to (3.9%) and (99.5%) for the transplanter before modifications. Average hill depositing index were (1.04, 1.07 and 1.09) versus finger speeds of 6.98, 7.85 and 8.96 m/s, compared to (1.03, 1.05 and 1.06) for the transplanter before modification,     The actual hill space in row were varied from the adjusted one by an average decrement rate of 6.9 and 7.5 % for the machine before and after modification. Average row spaces after modification were ( 19.96, 20 and 20.1 cm) versus finger speeds of 6.98, 7.85 and 8.96 m/s, with standard deviation of  (±0.61, ± .71 and  ± 0.87) respectively.    The grain yield and straw yields were almost more that before developing by 26 % .