We studied the reproductive ecology of the slider turtle. Trachemys scripta callirostris, during the reproductive season of the year 2000, in an area of the Mompós Depression, northern Colombia. We examined the number of nests ovoposited in locations with different characteristics, their hatching success rates and the natural causes of egg mortality. We also determined the effects of exploitation of nesting females, in two populations with different levels of harvesting. The results showed that the majority of nests were laid along bodies of water, in the first 20 m of the shoreline, in sites with substrates of moderate humidity, sand and clayish texture, covered by creeping vegetation. Invertebrates produced the greatest mortality in the nests. Hatching success was high, compared to other reports for this species. Only in the site with the highest hunting pressure a negative correlation was found, between the harvest rate and the time elapsed since the start of the nesting period, suggesting that the excessive extraction decreased the number of nesting females. Also, the females from the highly exploited site were significantly smaller than those from the less exploited site. The females, neonates and nests of the entire area, exhibited sizes below that reported for other tropical populations of the genus. The continued hunting pressure in northern Colombia, appears to be a factor that has altered the structure and population dynamics of T. scripta callirostris.