Monitoring of inline intravenous pressure as a method for predicting or detecting infiltration of peripheral catheter sites in infants was evaluated. Inline intravenous pressure was measured every 30 minutes in infants less than 12 months of age who had standardized peripheral catheters through which they were receiving a continuous infusion. Pressure was measured by an inline pressure transducer, and the signal was recorded by a strip chart recorder. Physical activities or manipulations of the patients were recorded simultaneously with each pressure reading. The catheter site was inspected hourly for clinical signs of infiltration. There was no significant difference in baseline or final pressure measurements between patients whose catheter sites became infiltrated (n = 20) and patients whose catheter sites did not (n = 22). Likewise, changes in pressure from baseline did not differ between the infiltrated and noninfiltrated groups. At 12 hours before the final reading, pressures for the infiltrated group did not differ significantly from pressures for the noninfiltrated group, nor did these values differ from the respective baseline values. Over the final 12 hours of catheterization, mean slopes (changes in pressure over time) for the two groups did not differ significantly from 0 or from each other. Intrapatient specificity and sensitivity of the method and the false-alarm rate were clinically unacceptable. Monitoring of inline intravenous pressure is not useful for predicting or detecting infiltration of peripheral catheter sites in infants.