Background: In the present study we identified the relationships of the environmental variables air humidity and the noise measured objectively, with the stress' perception, the measured exhaustion and the physical valuation with instruments of self report, in addition to the time of delay in the patients who attended for their care in three different waiting rooms at a hospital in Mexico city. Method of inquiry: There is a growing literature today that offers empirical data on psychological and environmental characteristics of hospital settings (Topf, 2000; Zimring, 2004) stressing the negative effects they might have on patients' well-being and, in some cases, on some physiological indicators of health recovery; Reidl, Ortega & Estrada (2002) report a study which had the aim of identifying the relationship existing between physical, physiological and socio-environmental variables and their relationship with the stress valuation of patients. Results indicated the need to consider the waiting rooms as focal points in planning and environmental design of health centers and is of special importance for health institutions in Mexico, as they provide service to a great number of users and patients are obliged to spend long hours waiting in an environment that does not provide basic satisfactory conditions. Findings & Conclusions: The results identified significant relations between the physical valuation waiting rooms and the humidity (r = 309, p = 00), the level of noise (r = -,177, p = 03), stress' perception (r = -,193, p = 01), the exhaustion (r = -,186, p = 01) and with the time of delay (r = -,136, p = 05); there are additionally significant differences of the physical valuation among the three waiting rooms (F(2,209) = 5,98, p = 00). It means that, when the patients valued positively their environment, it was an optimal physical humidity conditions and lower noise; at the same time the patients reported a lower level of stress and exhaustion, and a short time of previous delay to its medical care. The conclusions emphasize to reduce adverse environmental conditions, because if they are not lowering they can increase or aggravate the disease or they can be a threat for the process of recovery in patients who attend to health care centers.