Antibacterials are among the most commonly used drugs in veterinary medical practice. Among this class of therapeutic agents are the fluoroquinolones which have been widely employed both in veterinary and medical practices because of their excellent antibacterial activities and wide antibacterial spectrum. Despite these known beneficial effects of the fluoroquinolones, adverse reactions affecting several systems including the cardiovascular system have been reported. This study was designed to investigate the possible effect of two commonly used fluoroquinolone drugs, Ciprofloxacin and Levofloxacin on cardiac function in dogs using arterial blood pressure as clinical index Eight apparently healthy male dogs were equally and randomly divided into 2 groups. Ciprofloxacin and Levofloxacin were orally administered respectively to each group at the dosage of 25mg/kg twice daily for 14 days.Noninvasive blood pressure measurements were taken 30 minutes before administration and thereafter on days 2, 5, 7, 10 and 14 of treatment. Data were analysed using ANOVA at a confidence level of 95%. Following the administration of ciprofloxacin, there was a drop in pre-treatment mean systolic blood pressure from 149.8±20.7 mm Hg to 132.0±8.2 mmHg on day two and further to 122.0±20.9 mmHg on day five. After day five, a gradual increase in the mean systolic blood pressure was observed on days 7 and 10 to 129.3±14.7 mmHg and 133.0±19.5 mmHg respectively. A further decrease in the mean systolic blood pressure was recorded on day 14 to 123.5±12.4mmHg. In the Levofloxacin group, a similar pattern was observed in dogs treated with an initial reduction of the pre-administration mean systolic blood pressure from 133.8±8.7 mmHg to 123.8±24.2 mmHg by day two of treatment and a rise to a peak of 145.8±10.0mmHg by day five of treatment. For these two treatment groups however, there were no statistically significant (p>0.05) differences between pre-administration and post-administration values recorded. Mean diastolic blood pressure decreased in the ciprofloxacin group from 82.5±8.5 mmHg to 62.5±10.7 mmHg by day two of treatment but increased to 77.8±12.1 mmHg and 83.8±10.2 mmHg by days 5 and 7 respectively. Levofloxacin also caused a decrease in the mean diastolic blood pressure from 81.3±12.1 mmHg to79.8±9.3 mmHg on day 2 of treatment. These values increased to 98.5±11.3 mmHg by day five of treatment. There were no statistically significant (p>0.05) differences between pre-administration and post-administration Mean Arterial Pressure values for both groups. From this study ciprofloxacin and levofloxacin did not appear to have any adverse effects on arterial blood pressure values in dogs at the dosage administered. Further work is however required to evaluate the possible effect of longer periods of treatment and higher dosages on blood pressure.