To assess the effectiveness of the 'Green Prescription' (GRx) program in promoting self-reported health benefits in previously inactive individuals, between 2001 and 2002, a retrospective survey was administered to 124 GRx patients throughout New Zealand. Participants were a non-randomized subset of a larger GRx population. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI) for differences in health outcomes between participants who had increased physical activity levels compared to participants who had decreased or not altered activity levels since first being prescribed the GRx. Completed surveys were obtained from 124 of 263 eligible participants; a response rate of 47%. Fifty-six percent of participants reported increases in physical activity levels after the GRx program, with 70% still undertaking some form of physical activity. Participants accumulated at least 30 minutes of physical activity per day on 3.4 +/- 2.5 days (mean +/- SD) per week. Participants who reported increased physical activity levels after the GRx reported substantially higher energy levels and improved breathing when compared to participants who reported less or about the same physical activity after the GRx intervention. Increased physical activity in GRx patients was associated with greater perceived health benefits. Effective and ongoing support networks were seen as important for behavior change.