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In spite of the increasing number of demographic studies about freshwater turtles, very few have been focused on populations in semi-arid regions. Therefore, the aim of this study is to estimate the demographic parameters of testudine species in an area of Caatinga, North East Brazil, while focusing on the following objectives: (i) To estimate the size of the populations; (ii) to assess the sex ratio and sexual dimorphism; (iii) to correlate biological parameters with temperature and rainfall data. Sampling was carried out over 12 months, from August 2011 to July 2012, for a total of five days per month. Hoop traps and chicken bait were used for sampling. In total, 63 specimens from three different species were captured: 44 specimens of P. geoffroanus; nine specimens of Kinosternon scotpioides and 10 specimens of Mesoclemmys tuberculata. The population densities were as follows: approximately 9 turtles/ha to P. geoffroanus, 2 turtles/ha to M. tuberculata and 2 turtles/ha to K. scorpioides. 50% of recorded captures occurred in February and March 2012. P. geoffroanus exhibited a sex ratio of 1.53(female):1(male) (P=0.223), whereas the ratio for K. scorpioides was 1(female):1.25(male). Sexual dimorphism index, calculated using the mean number of male and female carapaces, was 1.06 (deviated for females) for P. geoffroanus and 1.04 (deviated for males) for K. scopioides. It was not possible to deduce the sexual dimorphism or the sex ratio for M. tuberculata as only female specimens were captured. The data reported herein will be useful in the composition of management and conservation plans for testudirte species found in areas of Caatinga, as well as for further studies in this morphodimatic domain, which minimally studied in Brazil.