Objective: To investigate the effect of coffee consumption on some liver function indices in adult male and female Nigerians. Subjects and Methods: Thirty apparently healthy subjects, consisting of 18 men and 12 women, were made to consume 2 g of coffee daily for a total of 30 days. Activities of aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and plasma concentrations of total and conjugated bilirubin, total protein and albumin were determined using standard methods. Results: Relative to baseline values, coffee consumption raised mean levels of ALT by 4 IU/l (p < 0.001), AST by 2.0 1 U/l (p < 0.001), ALP by 3.0 1 U/l (p < 0.01), total bilirubin by 0.90 mg/dl (p < 0.05) and total protein by 1.1 g/l (p < 0.05). Gender differences were observed. Significantly higher mean ALP concentration was only seen in male subjects, while mean bilirubin concentration was significantly raised in female volunteers alone. On the other hand, the mean total protein and albumin concentrations in individual male and female groups were not significantly altered (p > 0.05 in each case). Conclusion: The result obtained from the study suggests that short-term consumption of coffee might have a significant effect on the integrity of the liver function tests studied.