This paper demonstrates for the first time that prisons with a higher proportion of natural vegetation within their perimeter have lower levels of staff sickness absence. It makes three significant contributions. First, it extends studies of workplace nature contact into the un-researched carceral context. Second, whereas previous workplace nature contact studies have largely utilized single-site surveys, it presents national-level, statistically robust analysis. Third, it brings a novel new perspective to studies of sickness absence within correctional workforces, by considering the effect of the physical environment. Econometric estimations presented in the paper confirm lower levels of staff sick-leave in prisons with more greenspace. This relationship persists when we control for prison size, security level, age, level of crowding, levels of self-harm and violence among prisoners, and assaults against staff. The findings are significant in demonstrating the benefits of nature contact in workplaces in general, and carceral environments in particular. Importantly, this has the potential to influence future prison design.