While the theoretical basis for a relationship between ground and environmental conditions and injury in rugby league is compelling, corroborative research is far from substantive. This study investigated the relationship between environmental and ground conditions and injury risk in 156 semi-professional rugby league players. Injuries were prospectively recorded from 157 training sessions and 137 competitive matches played over two consecutive competitive seasons. Daily weather variables (maximum and minimum temperature, relative humidity, and rainfall) were recorded, while ground conditions were subjectively rated as heavy, slippery, firm, or hard. Regression analysis was conducted to examine the independent effects of the environmental variables, ground condition, session type (training, match), and the interaction between ground condition and session type on injury. Higher temperatures, greater humidity, and greater levels of rainfall were all associated (p<.05) with softer ground conditions. A higher 365-day rainfall was associated with fewer injuries. Both the number of injuries and injury rate were higher in matches than in training sessions and when ground conditions were harder. For both number of injuries and injury rate, there was a statistically significant interaction between ground condition and session type, with harder ground conditions resulting in a higher injury rate in matches, but not training sessions. In conclusion, in rugby league, ground conditions do not influence training injuries, however, both harder ground conditions and less rainfall are associated with a greater number of match injuries.