The occupants of a glasshouse office with plants were tested four times (quarterly) against occupants of an 'Office Landscape' for impressions about their entire room, their working place, their subjective health and mood. The strongest difference in favour of the glasshouse concerned the inventiveness, good atmosphere, invitingness, naturalness, aliveness, harmony and colorfulness of the room (p< .001) and the healthiness, good smelling, moisture of air, agreeable temperature, stimulation, and pleasant light of the working place (p < .001). There were significant correlations between healthiness of the working place and good mood, lack of complaints about nervousness, blood circultion troubles and frequent colds.