several biological parameters related to the triatoma mexicana life-cycle were evaluated in this study. three cohorts were maintained under different combinations of temperature and relative humidity (rh): 25oc/50% rh; 25oc/75% rh; and 30oc/75% rh. observed hatching rates varied from 49-57.5% whereas the average time of hatching varied from 19.5-22.7 days. in the three cohorts studied, the mean time-lapse between presentation of the blood meal and the beginning of feeding was less than 5 min in all instars; the mean feeding time was longer than 10 min in all the instars; the post-feed defecation delay was over 10 min in all the instars. less than 50% of nymphs in each cohort completed the cycle and the average time from 1st instar nymph to adult was more than 255 days for the three cohorts. the number of blood meals before molt at each nymphal instar varied from 1-9. our results appear to indicate a lack of influence of temperature and rh on the biological parameters of t. mexicana that were studied, which could reflect the adaptation capacity of this species. we also conclude that t. mexicana can not be considered an effective transmitter of trypanosoma cruzi to human populations in areas where this species is currently present.