Objective: To test the hypothesis that heat stress peri-insemination skews towards female the secondary sex ratio in dairy cattle. In addition, the effect of heat stress peri-insemination on birth weight of resultant calves was investigated. Methods: Data on the date of insemination and sex and birth weight of the resultant calf were collected for a total of 934 single births on a crossbred dairy farm and grouped into thermoneutral and heat stress peri-insemination groups on the basis of temperature humidity indices on the day of insemination. Results: Logistic regression revealed no difference in the secondary sex ratios between thermoneutral (53.4:46.6) and heat stress (52.5:47.5) peri-insemination groups. These sex ratios were not different from the expected 50:50 ratio on Chi-square goodness of fit test. Differences in birth weight of calves between thermoneutral and heat stress peri-insemination groups did not approach statistical significance.Conclusions: These results indicate that heat stress peri-insemination does not affect secondary sex ratio and calf birth weight in crossbred dairy cattle.